Net-type drying device

Abstract

To provide a net-type drying device of an energy-saving type with heat efficiency improved by using heated air present in a drying chamber efficiently.SOLUTION: The net-type drying device comprises a heating chamber generating heated air, a drying chamber drying an object to be dried, a net-shaped belt conveyer allowing the object to be dried placed thereon to pass through the inside of the drying chamber, an introduction mechanism allowing the heated air generated in the heating chamber to pass through the net-shaped belt conveyer from below to above to introduce the same into the drying chamber, and a return mechanism allowing the heated air to pass through the net-shaped belt conveyer from above to below from the drying chamber to return the same to the heating chamber.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a net-type drying device for drying objects to be dried such as agricultural products, aquatic products, and granular chemical products on a moving net.

Background Art

[0002] In the production of processed foods, various processing steps such as heating, cooling, or drying are performed on food raw materials such as agricultural products and aquatic products. Among these, the "drying step" of removing moisture in food is a very important processing step because it is related to improving the quality, storability, and transportability of processed foods. For example, in tea production, the tea leaves are heated to inactivate the oxidase contained in the raw tea leaves, and then the tea leaves are dried so as to have a moisture content suitable for a predetermined subsequent processing step. On the other hand, at the tea production site, in order to improve production efficiency, it is required to quickly process a large amount of raw tea leaves.

[0003] In Patent Document 1 and Patent Document 2, a so-called net-type drying device has been proposed as a drying device that enables mass production of rough tea, improves drying efficiency, and can reduce production costs without impairing quality. This net-type drying device has a net-like belt conveyor (net belt) for transporting tea leaves in a drying chamber, and a hot air generating device for blowing hot air into this drying chamber. The tea leaves are placed on the net-like belt conveyor and continuously transported, and are dried by exposing them to the air heated by the hot air generating device, so continuous drying processing can be performed, and it is suitable for mass production.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, food raw materials such as tea leaves, agricultural products, and fishery products contain a large amount of moisture, so a large amount of energy is consumed in the drying process. Further, as shown in Patent Document 2, in a conventional net-type drying device, a large amount of hot air is constantly supplied from a hot air generating device into the drying chamber, and the supplied hot air contacts the tea leaves on the belt conveyor to take away the moisture of the tea leaves, and then is discharged outside the device from an exhaust damper provided at the upper part of the drying chamber. According to this structure, the thermal efficiency decreases by the amount of air in the drying chamber discharged outside the device from the exhaust damper, so improvement of the thermal efficiency has been desired. In recent years, the impact of climate change on human society has been regarded as a problem, and in food processing as well, there is a demand for manufacturing devices that more consider the impact on the global environment, such as reducing the amount of fuel used in drying processing to suppress carbon dioxide emissions.

[0006] In view of such circumstances, the present invention has been made, and an object thereof is to provide an energy-saving type net-type drying device with improved thermal efficiency by efficiently using the heated air in the drying chamber.

Means for Solving the Problems

[0007] The present inventor has been conducting research and development on a structure that can efficiently use the heated air in the drying chamber in order to improve the thermal efficiency of the net-type drying device. More specifically, for example, regarding the net-type drying device shown in Patent Document 2, an aggregation part of the heated air exhausted above an exhaust damper provided at the upper part of the drying chamber is provided, and a hot air circulation structure in which the heated air aggregated here is circulated to the hot air generating device side through a duct has been proposed. However, in such a circulation structure, it has been found that not only does the upper part of the drying device become large, but also the precious heat is taken away while the heated air is circulating in the duct, resulting in loss of thermal energy. Therefore, the present inventor has conducted research and development on a circulation structure that can efficiently use the heated air in the drying chamber while avoiding an increase in the size of the drying device itself, and as a result, the present invention has been completed.

[0008] In order to achieve the above object, the net-type drying apparatus according to the present invention includes a heating chamber that generates heated air, a drying chamber that dries an object to be dried, a net-shaped belt conveyor that passes through the drying chamber with the object to be dried placed thereon, an introduction mechanism that allows the heated air generated in the heating chamber to pass from below the net-shaped belt conveyor to above and introduces it into the drying chamber, and a return mechanism that allows the heated air to pass from above the net-shaped belt conveyor to below the drying chamber and returns it to the heating chamber.

[0009] With such a configuration, the heated air for drying the object circulates between the heating chamber and the drying chamber. The heated air still has a high temperature even after being introduced into the drying chamber, and by heating the heated air sent back to the heating chamber again by the return mechanism, the amount of heat consumed by the heating chamber can be reduced and the thermal efficiency can be improved. In addition, since the heated air passes from below to above and from above to below the net-shaped belt conveyor on which the object is placed, the object can be dried very efficiently. Furthermore, by configuring the heated air to pass from below the net-shaped belt conveyor to above and be introduced into the drying chamber, and to pass from above the drying chamber to below the net-shaped belt conveyor and be returned to the heating chamber, it becomes possible to shorten the circulation path of the heated air. As a result, the thermal energy lost when the heated air circulates can be reduced, and it is also possible to realize miniaturization of the apparatus. Moreover, the heated air that has passed through the drying chamber contains water vapor by taking moisture from the object, and thus becomes humid hot air by being reheated in the heating chamber. The humid hot air is said to have an extremely high heat transfer rate compared to mere hot air (heated air), and the temperature of the object can be raised to a high temperature in a short time. The net-type drying apparatus according to the present invention can generate humid hot air without providing a steam boiler in the drying apparatus. By using this humid hot air for drying the object, the temperature of the object can be effectively raised, so that the object can be sufficiently dried and a decrease in quality can be avoided.

[0010] It further includes a support base for slidably supporting a net-shaped belt conveyor. The introduction mechanism is configured to introduce heated air into the drying chamber by passing it through an introduction through-hole provided in the support base and the net-shaped belt conveyor. The return mechanism is preferably configured to send the heated air in the drying chamber into the heating chamber by passing it through the net-shaped belt conveyor and an outlet through-hole provided in the support base.

[0011] By configuring it in this way, a flow of heated air is preferably formed inside the net-type drying device. That is, the heated air introduced from the introduction mechanism passes through the object from below the feed belt, and the heated air introduced into the drying chamber passes through the object and is sucked below the feed belt. Therefore, the heated air can be well used for drying the object, and efficient drying can be performed.

[0012] It is also preferable that the introduction through-hole and the outlet through-hole are provided at different and adjacent positions on the support base. By arranging the introduction through-hole and the outlet through-hole adjacent to each other, the circulation path of the heated air can be made shorter, and the loss of thermal energy can be reduced.

[0013] It is also preferable to further include a partition wall provided between the introduction through-hole and the outlet through-hole, which separates the supply flow path of the heated air leading from the heating chamber to the introduction through-hole and the return flow path of the heated air leading from the outlet through-hole to the heating chamber. By providing such a partition wall, the heated air generated in the heating chamber can be reliably introduced into the drying chamber, and drying can be performed efficiently.

[0014] It is also preferable to include a fan for urging the heated air flowing through the introduction mechanism and the return mechanism. By providing such a fan, it is possible to send the heated air from the heating chamber into the drying chamber and suck the heated air inside the drying chamber back into the heating chamber.

[0015] In this case, it is preferable that the fan is provided in the flow path of the return mechanism. If the fan is provided in the flow path of the return mechanism, the temperature of the heated air is lower than when it is provided in the flow path of the introduction mechanism, so the influence of the heat applied to the fan can be reduced.

[0016] In this case, it is preferable that the return mechanism is provided with a filter for removing dust carried by the heated air in the flow path of the heated air leading from the lead-out through-hole to the fan. During drying, if a part of the object becomes dust and is carried by the heated air, it may enter the driving parts such as the fan and the heating chamber, which may cause a failure. However, by providing such a filter, it is possible to prevent the intrusion of dust into the fan and the heating chamber.

[0017] Furthermore, in this case, it is preferable that the return mechanism is provided with a rectifying plate arranged to intersect in the direction in which the heated air flows so as to block a part of the flow path between the lead-out through-hole and the filter. By providing such a rectifying plate, the backflow of the heated air sucked from the lead-out hole can be suppressed, and good drying of the object can be achieved.

[0018] It is also preferable that the drying chamber has a stirring part for scraping up and stirring the object placed on the net-like belt conveyor, and the lead-out through-hole is arranged vertically below the stirring part. Due to the stirring operation of the stirring part, the layer of the object is thinner below it, so the heated air is easily sucked out from the lead-out through-hole, and a good flow of the heated air can be formed. In addition, since the heated air is sucked downward in the stirring part, the powder generated when stirring the object is sucked together with the heated air, so dust is less likely to be generated in the drying chamber.

[0019] It is also preferable that the support base is provided with a plurality of air guide plates below the introduction through-hole. By providing the air guide plates in this way, the heated air can be well guided into the drying chamber, and the object can be dried homogeneously.

[0020] It is also preferable that the drying chamber has an inlet and an outlet of a net-shaped belt conveyor for continuously conveying the object inside. By providing the inlet and the outlet in this way, drying of a large amount of objects can be continuously performed.

[0021] It is also preferable that an exhaust damper for partially opening the flow path of the heated air is arranged on the ceiling of the drying chamber. By arranging the exhaust damper in this way, the temperature and humidity in the drying chamber can be adjusted.

[0022] It is also preferable that the heating chamber and the fan are housed in the lower part of the support base. By housing them in the lower part of the support base in this way, miniaturization of the net-type drying device can be achieved.

Advantages of the Invention

[0023] According to the present invention, mainly, a net-type drying device having the following excellent effects can be provided. (1) The thermal efficiency of drying the object can be improved. (2) The object can be dried very efficiently. (3) Since the circulation path of the heated air can be shortened, the heat energy lost when the heated air circulates can be reduced, and miniaturization of the device can be achieved.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

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Figure 13

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The illustrated content is only schematically and exemplarily shown for the understanding of the present invention, and the appearance and dimensional ratios may be different from the actual ones. Further, although it will be specifically described by the embodiments below, the present invention is not limited to these embodiments.

[0026] As shown in FIG. 1, this embodiment is an example of a drying line 1 that dries the tea leaves 110, which are the objects to be dried, while conveying them. The drying line 1 is provided with a plurality (two in this example, but not limited to this number) of net-type drying devices 2. This drying line 1 is configured to dry the tea leaves with heated air while continuously conveying them with a belt conveyor. The heated air for drying the tea leaves is configured to circulate between the heating chamber and the drying chamber. Therefore, it is possible to configure a tea leaf production line with improved thermal efficiency and energy savings.

[0027] In the drying line 1 of this embodiment, two net-type drying devices 2 are connected. An input section 3 for feeding the tea leaves 110 into the drying line 1 is provided at one end, and an output section 4 for discharging the dried tea leaves 111 from the drying line 1 is provided at the other end. The belt conveyor 100 for placing and conveying the tea leaves 110 and 111 is composed of a feed belt 101 and a return belt 102. The feed belt 101 passes through the drying chamber 20, and the return belt 102 passes under the heating chamber 10 and the fan 90. It is looped around the drive section 5 and a plurality of pulleys 6. The belt conveyor 100 is composed of a net-like belt (net belt), and is configured such that gas can pass through this belt in the vertical direction through small holes formed by the mesh. In this embodiment, the belt conveyor 100 is an endless belt and is formed of a metal material such as a heat-resistant synthetic resin or stainless steel. In the drying line 1, by rotating the drive section 5, the feed belt 101 can be moved in the conveying direction D. Therefore, the tea leaves 110 and 111 placed on the feed belt 101 at the input section 3 are conveyed in the conveying direction D and discharged from the output section 4.

[0028] Next, the net-type drying device 2 that constitutes the drying line 1 according to the present embodiment will be described in detail. FIGS. 2 and 3 schematically show the configuration of the net-type drying device 2 of the present embodiment. As shown in these figures, the net-type drying device 2 includes a heating chamber 10, a drying chamber 20 for drying the tea leaves during conveyance, a support base 40 that slidably supports the feed belt 101 of the belt conveyor 100 from below, an introduction mechanism 60 for introducing heated air into the drying chamber 20, and a return mechanism 80 for discharging the heated air from the drying chamber 20 and sending it to the heating chamber 10. The drying chamber 20 has a ceiling 22 and side walls 24, and the upper and side portions of the feed belt 101 are surrounded within the drying chamber 20 by these ceiling 22 and side walls 24. The drying chamber 20 is formed with an inlet 26 and an outlet 28 for the feed belt 101, and is configured such that the tea leaves 110 are continuously passed and conveyed through the drying chamber 20 surrounded by the ceiling 22 and side walls 24. An exhaust damper 23 is disposed on the ceiling 22, and as shown in FIG. 4, by opening the exhaust damper 23, it is possible to adjust the temperature and humidity inside the drying chamber 20. Note that, as shown in FIGS. 2 and 10, a wind shield 36 may be provided so that heated air does not leak from the inlet 26 or the outlet 28.

[0029] Next, the heating chamber 10 will be described. FIGS. 5 and 6 schematically show the internal structure of the net-type drying device 2. The net-type drying device 2 has a heating chamber 10 that generates heated air G for drying the tea leaves. As shown in FIG. 5, a gun-type gas burner 12 is attached to the heating chamber 10 as a means for heating air. The gun-type gas burner 12 heats the air inside the heating chamber 10 to 70°C to 400°C with its flame, thereby generating the heated air G.

[0030] Next, the introduction mechanism 60 will be described. As shown in FIGS. 5 and 6, the introduction mechanism 60 in the present embodiment includes a discharge duct 62 and a plurality of supply ducts 64 that constitute a supply flow path of the heated air G from the heating chamber 10 to the drying chamber 20. The plurality of supply ducts 64 extend in a direction crossing the transport direction D from the discharge duct 62, and the discharge duct 62 communicates the plurality of supply ducts 64 with the heating chamber 10. The plurality of supply ducts 64 introduce the heated air into the drying chamber 20 through the introduction through-holes 46 of the support base 40 and the mesh of the belt conveyor 100. By configuring in this way, the heated air G can be efficiently supplied from the heating chamber 10 to the drying chamber 20.

[0031] Next, the support base 40 will be described. FIGS. 7 and 8 schematically show the configuration of the support base 40 that slidably supports the belt conveyor 100. As shown in these figures, a plurality of introduction through-holes 46 for introducing the heated air G into the drying chamber 20 are formed in the support base 40. In each introduction through-hole 46, a plurality of air guide plates 42 are arranged in parallel with each other so as to cross the supply duct 64. As a result, the introduction through-hole 46 is partitioned into a plurality of narrow through-holes extending along the transport direction D. These air guide plates 42 are arranged such that their upper ends are substantially in the same plane, and are configured to slidably support the feed belt 101 of the belt conveyor 100 at their upper ends. Each air guide plate 42 has a longer vertical length as it moves away from the discharge duct 62, and guides the heated air G from the supply duct 64 to the introduction through-hole 46. By configuring in this way, the introduction through-hole 46 is divided into a plurality in the direction crossing the transport direction D, and the same amount of heated air G is introduced into the drying chamber 20 through the mesh of the feed belt 101 of the belt conveyor 100 from the divided through-holes.

[0032] Further, at a position different from and adjacent to the introduction through-hole 46 of the support base 40, a lead-out through-hole 48 for leading the heated air G from the drying chamber 20 to the discharge duct 82 is formed. A rod-shaped support 44 is disposed at the lead-out through-hole 48 so as to cross the conveyance direction D. The rod-shaped support 44 is disposed substantially in the same plane as the upper end of the air guide plate 42 and slidably supports the feed belt 101. By configuring in this way, it is possible to prevent the feed belt 101 from being deflected at the position of the lead-out through-hole 48 due to the stirring operation of the stirring unit 30 described later and the like.

[0033] Next, the return mechanism 80 will be described. FIGS. 9 and 10 schematically show the configuration of the return mechanism 80. As shown in these figures, the return mechanism 80 includes a fan 90 that sucks the heated air G inside the drying chamber 20 through the mesh of the feed belt 101 of the belt conveyor 100 and the lead-out through-hole 48 and sends the heated air G from the heating chamber 10 into the drying chamber 20, and a plurality of discharge ducts 82 and recovery ducts 84 that constitute a suction flow path of the heated air G from the lead-out through-hole 48 to the fan 90. One ends of the plurality of discharge ducts 82 extend in a direction crossing the conveyance direction D and communicate with the plurality of lead-out through-holes 48, and the other ends communicate with the recovery duct 84. That is, the recovery duct 84 communicates the plurality of discharge ducts 82 and the fan 90. The fan 90 sucks and recovers the heated air G from the drying chamber 20 through the mesh of the feed belt 101, the discharge duct 82, and the recovery duct 84 in sequence, and sends the recovered heated air G into the heating chamber 10. By configuring in this way, the heated air G can be efficiently recovered from the drying chamber 20 and reheated. If the fan 90 is provided in the flow path of the return mechanism, the temperature of the heated air G is lower than when it is provided in the flow path of the introduction mechanism, so the influence of the heat applied to the fan 90 can be reduced.

[0034] Below the lead-through opening 48 of the discharge duct 82, a flow rectifying plate 88 is arranged in a direction intersecting with the direction in which the heated air G flows so as to block a part of the suction passage. By providing such a flow rectifying plate 88, the reverse flow of the heated air G sucked from the lead-through opening 48 can be suitably suppressed. Further, as shown in FIG. 9, the flow rectifying plate 88 is fixed to the partition wall 50 so as to incline downward as it approaches the recovery duct 84, and a plurality of flow rectifying holes 89 are formed therein. The size of the flow rectifying holes 89 is not particularly limited, but in the present embodiment, they are formed so as to become smaller as they approach the recovery duct 84. By configuring in this way, regardless of the position of the lead-through opening 48, the heated air G with a substantially constant flow rate can flow from the lead-through opening 48 to the discharge duct 82, and the tea leaves can be dried uniformly.

[0035] As shown in FIG. 5, a dust removal filter 86 is arranged in the suction passage between the discharge duct 82 and the recovery duct 84. The type of the filter 86 is not particularly limited, but a metal filter with finer gaps than the mesh of the belt conveyor 100 is preferably used. By configuring in this way, the dust of the tea leaves carried by the heated air G can be removed. If a part of the tea leaves becomes dust and is carried by the heated air, this dust may enter the driving parts such as the fan 90 and the heating chamber 10 and cause a failure. That is, by arranging such a filter 86, the intrusion of dust into the fan 90 and the heating chamber 10 can be prevented. Further, as shown in FIGS. 2, 4, and 9, an intake damper 92 for taking outside air into the recovery duct 84 is arranged in the recovery duct 84. By opening the intake damper 92 as shown in FIG. 4, the outside air is taken into the recovery duct 84, and the temperature and humidity of the recovered heated air G can be adjusted. It should be noted that the intake damper 92 is preferably provided with a damper filter 93 for removing dust so that dust such as tea powder floating in the outside air is not taken into the recovery duct 84 together with the outside air.

[0036] As described above, the fan 90 is configured to suck the heated air G from the drying chamber 20 through the mesh of the feed belt 101, the discharge duct 82, and the recovery duct 84 in sequence, and send it into the heating chamber 10, and also send the heated air G from the heating chamber 10 into the drying chamber 20. The type of the fan 90 is not particularly limited, but in the present embodiment, from the viewpoint of ensuring the air volume for sucking and recovering the heated air G in the drying chamber 20, it is preferably a multi-blade blower in which vertically long blades are assembled in a cylindrical shape. A propeller fan may be used instead of the multi-blade blower. FIG. 11 schematically shows the configuration around the fan 90. The fan duct 91 shown in the figure constitutes a flow path communicating from the recovery duct 84 to the heating chamber 10, and functions to send the heated air G sucked and recovered from the drying chamber 20 into the heating chamber 10.

[0037] As described above, in the present embodiment, the feed belt 101 is slidably supported by the support base 40, more specifically, by the upper end of the air guide plate 42 disposed at the introduction through-hole 46 and the rod-shaped support 44 disposed at the discharge through-hole 48. Further, the drying chamber 20 composed of the ceiling 22 and the side wall 24 is formed above the support base 40. The belt conveyor 100 is looped and supported so as to convey the tea leaves 110 placed on the feed belt 101 from the inlet 26 to the outlet 28 of the drying chamber 20. In the net-type drying device 2, the flow path of the heated air G (heating chamber 10, discharge duct 62, supply duct 64, drying chamber 20, discharge duct 82, recovery duct 84, and fan duct 91) is closed except for the inlet 26 and the outlet 28. Therefore, in the present embodiment, the heated air G is less likely to leak from the net-type drying device 2, and the suction force by the fan 90 easily acts on the heated air G in the entire flow path. Accordingly, it is easy to create a flow of the heated air G in which the heated air G passes through the tea leaves 110 from below the feed belt 101, and the heated air G introduced into the drying chamber passes through the tea leaves 110 and is sucked below the feed belt 101.

[0038] In this embodiment, a partition wall 50 that separates a supply duct 64 (supply flow path) and a discharge duct 82 (suction flow path) is formed between the introduction through-hole 46 and the discharge through-hole 48, and thus heated air G can be reliably introduced from the supply duct 64 into the drying chamber 20. Therefore, the heated air G can be efficiently used for drying without waste. In this embodiment, an exhaust damper 23 is disposed on the ceiling 22 of the drying chamber 20, and an intake damper 92 is disposed in the recovery duct 84. Therefore, if necessary, the flow path of the heated air G can be partially opened to exchange with outside air, and thus the tea leaves can be dried with suitable heated air. More specifically, for example, when the intake damper 92 is opened, outside air is taken into the recovery duct 84 by the suction action of the fan 90, and when the exhaust damper 23 is opened, the heated air G is discharged from the inside of the drying chamber 20 to the outside. Further, in this embodiment, both the exhaust damper 23 disposed on the ceiling of the drying chamber 20 and the intake damper 92 disposed in the recovery duct 84 are composed of opening and closing doors that can continuously or stepwise adjust their opening amounts (opening levels). Therefore, by adjusting the opening amount of the intake damper 92 and the opening amount of the exhaust damper 23, the air volume of the heated air G circulating in the apparatus 2, the temperature, and the humidity of the heated air G can be adjusted.

[0039] The net-type drying apparatus 2 of this embodiment is configured to introduce heated air G into the drying chamber 20 through the mesh of the feed belt 101 and the introduction through-hole 46, and to discharge the heated air G that has convected inside the drying chamber 20 from the drying chamber 20 through the mesh of the feed belt 101 and the discharge through-hole 48. Therefore, the heated air 101 can be used for drying the tea leaves 110 without waste, and efficient drying can be performed. Further, since both the entry and exit of the heated air G to and from the drying chamber 20 are below the support base 40, the circulation path of the heated air G can be shortened. As a result, the thermal energy lost when the heated air G circulates can be reduced. In this embodiment, the heating chamber 10 and the fan 90 are housed in the lower part of the support base 40. By configuring in this way, the configurations of the heating chamber and the duct do not become large, and miniaturization of the net-type drying apparatus can be achieved.

[0040] As shown in FIGS. 1 and 10, in this embodiment, a stirring unit 30 is disposed in the drying chamber 20. The stirring unit 30 is configured by attaching blades 34 around a rotating shaft 32. The blades 34 are composed of a plurality of blade-like members, and the tips are bent at a predetermined angle. By rotating the stirring unit 30 by driving means such as a motor, the tea leaves 110 being conveyed can be scraped up and loosened. The lead-out through port 48 is disposed vertically below the stirring unit 30. Due to the stirring operation of the stirring unit 30, the layer of tea leaves 110 placed and conveyed on the feed belt 101 becomes thinner below it, so that the heated air G is easily sucked out from the lead-out through port 48, and a good flow of the heated air G can be formed. Further, since the heated air G is sucked downward in the stirring unit 30, the tea powder generated when stirring the tea leaves is sucked together with the heated air G, so that dust is less likely to be generated in the drying chamber 20.

[0041] Note that, as shown in FIGS. 2 and 3, an openable maintenance window 7 may be provided in the flow path of the heated air G (heating chamber 10, discharge duct 62, supply duct 64, drying chamber 20, exhaust duct 82, recovery duct 84, and fan duct 91). Even when tea leaf dust accumulates in the flow path, if the drying line 1 is stopped and the maintenance window 7 is opened, the net-type drying device 2 can be maintained. Further, a thermometer and a hygrometer may be appropriately arranged in the flow path of the heated air G. The temperature and humidity of the heated air G can be grasped by the thermometer and the hygrometer, which can be used as a guide for operating the gun-type gas burner 12, the exhaust damper 23, and the intake damper 92.

[0042] FIG. 12 schematically shows the flow of heated air in the net-type drying apparatus of the present embodiment. As shown in the figure, the heated air sent into the heating chamber 10 by the discharging action of the fan 90 passes through a plurality of supply ducts 64 from the discharge duct 62, passes through the introduction through-hole 46 of the support base 40, and passes through the mesh of the feed belt 101 of the belt conveyor 100 on which the tea leaves 110 to be dried are placed and conveyed, and is introduced into the drying chamber 20 from below upward. A discharge through-hole 48 is formed at a position adjacent to but different from the introduction through-hole 46 of the support base 40. The heated air in the drying chamber 20 passes through the mesh of the feed belt 101 from above downward by the suction action of the fan 90, passes through the discharge through-hole 48 of the support base 40, passes through a plurality of discharge ducts 82 and a recovery duct 84, and is returned to the heating chamber 10. The heated air G still has a high temperature even after being introduced into the drying chamber 20. By heating the heated air G sent back to the heating chamber 10 again by the return mechanism 80, the amount of heat required for the gun-type gas burner 12 in the heating chamber 10 can be reduced. Further, as shown in FIG. 13, since the heated air passes through the feed belt 101 on which the tea leaves 110, the object to be dried, are placed from below upward and from above downward, the tea leaves 110 can be dried very efficiently. Furthermore, the heated air G is passed through the introduction through-hole 46, passed through the belt conveyor 100 having a net shape from below upward and introduced into the drying chamber 20, passed through the belt conveyor 100 having a net shape from above downward in the drying chamber 20, and passed through the discharge through-hole 48 provided at a position adjacent to but different from the introduction through-hole 46 and returned to the heating chamber 10, so that the circulation path of the heated air G can be made shorter. As a result, the heat energy lost when the heated air G circulates can be reduced, and the size reduction of the apparatus can also be realized. Furthermore, since the heated air G that has passed through the drying chamber 20 contains water vapor by depriving the tea leaves 110 of moisture, it becomes humid hot air by being reheated in the heating chamber 10. Therefore, humid hot air can be generated without adding steam to the flow of heated air. By using the humid hot air for drying the tea leaves, the temperature of the tea leaves can be effectively increased, so that the tea leaves 110 can be sufficiently dried in a short time and the quality of the tea leaves can be maintained.

[0043] Furthermore, in the net-type drying apparatus of the present embodiment, an intake damper 92 capable of taking in outside air and an exhaust damper 23 capable of discharging the heated air G in the drying chamber 20 are provided. When the opening / closing door of the intake damper 92 is opened, outside air is taken into the recovery duct 84 by the suction action of the fan 90, and when the opening / closing door of the exhaust damper 23 is opened, the heated air G is discharged from the drying chamber 20 to the outside. Therefore, by adjusting the opening amount of the opening / closing door of the intake damper 92 and the opening amount of the opening / closing door of the exhaust damper 23, the air volume, temperature, and humidity of the heated air G circulating in the apparatus 2 can be adjusted. Therefore, the tea leaves to be dried can be dried under suitable drying conditions.

[0044] Although the above-described embodiment relates to a drying apparatus for drying tea leaves, the net-type drying apparatus of the present invention can be applied to the drying of, for example, agricultural products such as herbs, vegetables, and grains other than tea leaves, aquatic products such as wakame and kelp, and plastics and granular chemical products as objects to be dried.

[0045] The present invention is not limited to the above-described embodiment, and various forms with design changes within the scope not departing from the gist of the invention described in the claims are also included in the technical scope.

Industrial Applicability

[0046] The present invention can be widely applied to the drying of agricultural products such as tea leaves, herbs, vegetables, and grains, aquatic products such as wakame and kelp, plastics, and granular chemical products, and is widely useful in these processing industries.

Explanation of Reference Numerals

[0047] 1 Drying line 2 Net-type drying apparatus 3 Feeding section 4 Discharging section 5 Driving section 6 Pulley 7 Maintenance window 10 Heating chamber 12 Gun type burner 20 Drying chamber 22 Ceiling 23 Exhaust damper 24 Side wall 26 Inlet 28 Outlet 30 Stirring section 32 Rotating shaft 34 Blade 36 Wind shield 40 Support stand 42 Air guide plate 44 Rod-shaped support 46 Introduction through-hole 48 Discharge through-hole 50 Partition wall 60 Introduction mechanism 62 Discharge duct (supply flow path) 64 Supply duct (supply flow path) 80 Return mechanism 82 Exhaust duct (suction flow path) 84 Recovery duct (suction flow path) 86 Filter 88 Rectifying plate 89 Rectifying hole 90 Fan 91 Duct for fan (return flow path) 92 Intake damper 93 Damper filter 100 Belt conveyor 101 Feeding belt 102 Return belt 110, 111 Tea leaves

Claims

1. A heating chamber for generating heated air, A drying chamber for drying an object to be dried, A net-shaped belt conveyor for passing through the drying chamber with the object to be dried placed thereon, An introduction mechanism for introducing the heated air generated in the heating chamber from below to above the net-shaped belt conveyor into the drying chamber, A return mechanism for passing the heated air from the drying chamber from above to below the net-shaped belt conveyor and returning it to the heating chamber, A net-type drying device characterized by comprising the above.

2. Further comprising a support base for slidably supporting the net-shaped belt conveyor, The introduction mechanism is configured to introduce the heated air through an introduction through-hole provided in the support base and the net-shaped belt conveyor into the drying chamber, The return mechanism is configured to send the heated air in the drying chamber through the net-shaped belt conveyor and a discharge through-hole provided in the support base into the heating chamber, and the net-type drying device according to claim 1, characterized in that.

3. The net-type drying device according to claim 2, characterized in that the introduction through-hole and the discharge through-hole are provided at different and adjacent positions of the support base.

4. Further comprising a partition wall provided between the introduction through-hole and the discharge through-hole for separating a flow path for supplying heated air communicating from the heating chamber to the introduction through-hole and a flow path for returning heated air communicating from the discharge through-hole to the heating chamber, and the net-type drying device according to claim 2 or 3, characterized in that.

5. The net-type drying device according to claim 2 or 3, characterized in that it comprises a fan for urging the heated air flowing through the introduction mechanism and the return mechanism.

6. The net-type drying device according to claim 5, characterized in that the fan is provided in the flow path of the return mechanism.

7. The net-type drying device according to claim 6, characterized in that the return mechanism comprises a filter for removing dust carried by the heated air in a flow path of the heated air communicating from the discharge through-hole to the fan.

8. The net-type drying device according to claim 7, characterized in that the return mechanism comprises a rectifying plate disposed to intersect the direction in which the heated air flows so as to block a part of the flow path between the discharge through-hole and the filter.

9. The drying chamber has a stirring part that scrapes up and stirs the object placed on the net-shaped belt conveyor, and the outlet through-hole is arranged vertically below the stirring part. The net-type drying device according to claim 2 or 3, characterized in that.

10. The support base is provided with a plurality of air guide plates below the inlet through-hole. The net-type drying device according to claim 2 or 3, characterized in that.

11. The drying chamber includes an inlet and an outlet of the net-shaped belt conveyor that continuously conveys the object inside. The net-type drying device according to claim 1, characterized in that.

12. An exhaust damper that partially opens the flow path of the heated air is arranged on the ceiling of the drying chamber. The net-type drying device according to claim 1, characterized in that.

13. The heating chamber and the fan are housed in the lower part of the support base. The net-type drying device according to claim 5, characterized in that.

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