Drying System and Drying Method

Abstract

To provide a drying system low in frequency of maintenance and capable of continuously drying powder and grain.SOLUTION: A drying system 1 includes a flash dryer 21, a fluidized bed drying portion 23, a supply branch valve 22, and a collection portion 70. The flash dryer 21 dries powder and grain by making the powder and grain as an object to be dried and gas for drying the powder and grain flow to a drying passage 21a. The fluidized bed drying portion 23 is disposed at a downstream side with respect to the flash dryer 21, and dries the powder and grain stored in a first drying space 32 or a second drying space 42 by fluidizing and drying. The supply branch valve 22 can switch between a state of supplying the powder and grain dried by the flash dryer 21 to the first drying space 32 and a state of supplying the powder and grain dried by the flash dryer 21 to the second drying space 42. The collection portion 70 collects the powder and grain dried in the first drying space 32 and the second drying space 42.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention mainly relates to a drying system for drying powders and granules.

Background Art

[0002] Patent Document 1 discloses a fluidized bed drying apparatus for continuously drying powders and granules. The fluidized bed drying apparatus has a plurality of treatment chambers partitioned by partition walls. In each treatment chamber, powders and granules are sequentially supplied, and the powders and granules whose drying is completed are sequentially discharged.

[0003] Patent Document 2 discloses a drying apparatus in which an airflow drying machine is provided above a fluidized bed dryer. The material dried by the airflow drying apparatus is further dried by the fluidized bed dryer.

[0004] Patent Document 3 discloses an apparatus including an airflow drying tube and a dryer. Hot air flows through the airflow drying tube, and the object to be dried is dried by flowing the object to be dried through the airflow drying tube. The object to be dried dried in the airflow drying tube is supplied to the dryer. In the dryer, the object to be dried is dried by flowing the object to be dried in a superheated steam atmosphere.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the fluidized bed drying apparatus of Patent Document 1, since the granular material in a state of having a large amount of moisture is supplied to the processing chamber, the granular material easily adheres to the inner wall of the processing chamber. Therefore, it is necessary to perform maintenance for cleaning the inner wall of the processing chamber at a high frequency. In the apparatuses of Patent Documents 2 and 3, when continuously supplying the material to be dried to the fluidized bed dryer / drying chamber, the drying time of the material to be dried is not constant, so unevenness occurs in the drying of the material to be dried. However, when stopping the supply of the material to be dried to the fluidized bed dryer / drying chamber until the drying in the fluidized bed dryer / drying chamber is completed, the continuity decreases.

[0007] The present invention has been made in view of the above circumstances, and its main object is to provide a drying system with a low maintenance frequency and capable of continuously drying granular materials.

Means for Solving the Problems

[0008] The problems to be solved by the present invention are as described above. Next, the means for solving these problems and their effects will be described.

[0009] According to a first aspect of the present invention, a drying system having the following configuration is provided. That is, the drying system includes a pneumatic dryer, a fluidized bed drying section, a supply switching section, and a collection section. The pneumatic dryer has a drying path, and the granular material, which is an object to be dried, and a gas for drying the granular material are caused to flow through the drying path to dry the granular material. The fluidized bed drying section is provided downstream of the pneumatic dryer and has at least a first drying space and a second drying space, and the granular material accommodated in the first drying space or the second drying space is fluidized and dried. The supply switching section is capable of switching between a state of supplying the granular material dried by the pneumatic dryer to the first drying space and a state of supplying the granular material dried by the pneumatic dryer to the second drying space. The collection section collects the granular material dried in the first drying space and the second drying space.

[0010] According to a second aspect of the present invention, the following drying method is provided. That is, the drying method includes a pneumatic drying step, a fluidized bed drying step, and a collection step. In the pneumatic drying step, the granulated material, which is an object to be dried, and a gas for drying the granulated material are caused to flow through a drying path to dry the granulated material. In the fluidized bed drying step, the granulated material that has undergone the pneumatic drying step is supplied to a first drying space or a second drying space, and the granulated material accommodated in the first drying space or the second drying space is fluidized and dried. In the collection step, the granulated material dried in the first drying space and the second drying space is collected. A state in which the granulated material dried in the pneumatic drying step is supplied to the first drying space and a state in which the granulated material dried in the pneumatic dryer is supplied to the second drying space are switchable.

[0011] As a result, since the granulated material dried by the pneumatic dryer and having a reduced moisture content is supplied to the fluidized bed drying section, it is difficult for the granulated material to adhere to the inner wall of the fluidized bed drying section. Further, in the pneumatic dryer, the flow velocity of the gas in the path is high and the concentration of the granulated material with respect to the gas is low, so the surface of the granulated material is quickly dried and it is difficult for the granulated material to adhere to the inner wall of the path. As described above, in the above drying system, the maintenance frequency of both the pneumatic dryer and the fluidized bed drying section is reduced. Further, since there are a plurality of supply destinations for the granulated material dried by the pneumatic dryer, the waiting time for the granulated material can be made zero or short, so that the granulated material can be continuously dried.

Effects of the Invention

[0012] According to the present invention, it is possible to provide a drying system with a low maintenance frequency and capable of continuously drying granulated materials.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0014] Next, embodiments of the present invention will be described with reference to the drawings. First, with reference to FIGS. 1 and 2, the drying system 1 of the first embodiment will be described.

[0015] The drying system 1 is configured to include a plurality of devices for drying powder particles. The powder particles are a term indicating powders, granules (including granulated products), and mixtures of powders and granules. The powder particles may be pharmaceuticals or foods, or other substances. In the following description, the upstream / downstream of the flow of powder particles or gas may be simply referred to as upstream / downstream.

[0016] As shown in FIG. 1, the drying system 1 includes a supply unit 10, a drying unit 20, a blower unit 50, a suction unit 60, and a collection unit 70.

[0017] The supply unit 10 supplies the powder particles, which are the objects to be dried, to the drying unit 20. The powder particles supplied by the supply unit 10 contain a lot of moisture. The supply unit 10 includes a storage unit for storing the powder particles and a delivery unit for continuously delivering the powder particles. With this configuration, the supply unit 10 continuously supplies the powder particles to the drying unit 20.

[0018] The drying unit 20 dries the powder particles supplied by the supply unit 10. The drying unit 20 includes a pneumatic dryer 21, a supply branch valve 22, a fluidized bed drying unit 23, and a discharge branch valve 24.

[0019] The pneumatic dryer 21 has a housing, and a drying path 21a is formed inside the housing. The drying path 21a is an elongated path and includes curved, arc-shaped, or folded-back portions, etc. to increase the path length. The granular material supplied by the supply unit 10 flows through the drying path 21a. Further, high-temperature gas supplied by the air blowing unit 50 (details will be described later) flows through the drying path 21a. Thereby, as the granular material flows through the drying path 21a together with the high-temperature gas, the granular material is dried (primary drying).

[0020] The supply branch valve 22 is arranged on the downstream side of the pneumatic dryer 21 and on the upstream side of the fluidized bed drying unit 23. The fluidized bed drying unit 23 includes a first fluidized bed dryer 30 and a second fluidized bed dryer 40. The pipe on the upstream side of the supply branch valve 22 is connected to the pneumatic dryer 21. There are two pipes on the downstream side of the supply branch valve 22. One pipe is connected to the first fluidized bed dryer 30, and the other pipe is connected to the second fluidized bed dryer 40. Therefore, the supply branch valve 22 can switch between a state of supplying the granular material supplied from the pneumatic dryer 21 to the first fluidized bed dryer 30 and a state of supplying the granular material to the second fluidized bed dryer 40.

[0021] The operation of the supply branch valve 22 is controlled by the instruction device 100. The instruction device 100 includes a CPU, a ROM, a RAM, etc. The instruction device 100 can perform control related to the drying system 1 by reading the program stored in the ROM into the RAM and executing it. In the present embodiment, the supply branch valve 22 operates by an actuator such as a motor or a cylinder. The instruction device 100 can switch between a state of supplying the granular material to the first fluidized bed dryer 30 (Figure 1) and a state of supplying the granular material to the second fluidized bed dryer 40 (Figure 2) by giving an instruction to this actuator.

[0022] The granular material that has been primarily dried by the pneumatic dryer 21 is further dried (secondary drying) by the first fluidized bed dryer 30 or the second fluidized bed dryer 40. The ratio of the amount of moisture removed in primary drying and secondary drying is not particularly limited, but in this embodiment, the amount of moisture removed in primary drying is more than the amount of moisture removed in secondary drying. This is because it becomes difficult to remove moisture as the moisture ratio of the granular material decreases. However, the amount of moisture removed in primary drying may be less than the amount of moisture removed in secondary drying.

[0023] In contrast to the above-described pneumatic drying that dries the granular material in a one-way path, the fluidized bed drying unit 23 dries the granular material by supplying a high-temperature gas to a predetermined space and repeatedly fluidizing the granular material within the space.

[0024] Specifically, the first fluidized bed dryer 30 includes a first supply unit 31, a first drying space 32, and a first discharge unit 33. The first supply unit 31 is connected to the supply branch valve 22. The granular material dried by the pneumatic dryer 21 is supplied to the first drying space 32 via the supply branch valve 22 and the first supply unit 31. A high-temperature gas is supplied to the first drying space 32 by the blower unit 50. The high-temperature gas is supplied upward from the lower part of the first drying space 32. Thereby, the granular material can be fluidized in the first drying space 32. The granular material for which drying is completed in the first drying space 32 is discharged via the first discharge unit 33. Specifically, a discharge valve for switching whether or not to discharge the granular material is provided in the first discharge unit 33, and the granular material is discharged by switching the state of the discharge valve as instructed by the instruction device 100 at a predetermined timing.

[0025] The second fluidized bed dryer 40 includes a second supply unit 41, a second drying space 42, and a second discharge unit 43. Since the configuration of each part of the second fluidized bed dryer 40 is the same as the configuration of each part of the first fluidized bed dryer 30, the description thereof is omitted.

[0026] In this embodiment, the fluidized bed drying section 23 includes two fluidized bed dryers, but it may also be configured to include three or more fluidized bed dryers. Alternatively, instead of a configuration including a plurality of fluidized bed dryers, it may be configured to include one fluidized bed dryer having a plurality of drying spaces. In this configuration, the drying space is divided into a plurality of sections by partitions or the like provided in the fluidized bed dryer, and the granular material can be individually supplied to each drying space and discharged from each drying space individually.

[0027] The discharge branch valve 24 is disposed downstream of the fluidized bed drying section 23 and upstream of the collection section 70. The discharge branch valve 24 supplies the granular material supplied from the first fluidized bed dryer 30 or the second fluidized bed dryer 40 to the collection section 70. Specifically, there are two pipes on the upstream side of the discharge branch valve 24, one pipe is connected to the first discharge section 33, and the other pipe is connected to the second discharge section 43. The pipe on the downstream side of the discharge branch valve 24 is connected to the collection section 70. Therefore, the discharge branch valve 24 can switch between a state of supplying the granular material supplied from the first fluidized bed dryer 30 to the collection section 70 (FIG. 2) and a state of supplying the granular material supplied from the second fluidized bed dryer 40 to the collection section 70 (FIG. 1). Similar to the supply branch valve 22, the discharge branch valve 24 also operates according to the instruction of the instruction device 100.

[0028] Here, the pneumatic dryer 21 is a continuous drying device. The continuous type means a method in which the granular material is continuously supplied, dried while being sent out without storing the supplied granular material, and the granular material is discharged.

[0029] On the other hand, the fluidized bed drying section 23 is of the batch type. The batch type is a method in which a predetermined predetermined amount is taken as one unit and one unit of granular material is dried together. Therefore, first, a predetermined amount of granular material is supplied to the fluidized bed drying section 23 (specifically, the first fluidized bed dryer 30 or the second fluidized bed dryer 40), and drying starts after the supply of the granular material is completed. Then, after the drying is completed, all (i.e., the predetermined amount) of the granular material supplied to the fluidized bed drying section 23 is discharged together.

[0030] That is, while the pneumatic dryer 21 continuously discharges the granular material, the fluidized bed drying section 23 is not configured to continuously dry the granular material. Here, in a conventional drying system in which one fluidized bed dryer is provided on the downstream side of the pneumatic dryer, when the fluidized bed dryer is drying the granular material, it is necessary to stop the supply of the granular material to the fluidized bed dryer. As a result, the continuity of the drying of the granular material is reduced. In addition, if the granular material is continuously supplied to the fluidized bed dryer, granular materials with different degrees of drying are mixed, resulting in non-uniform drying, which is not preferable.

[0031] In this regard, in the present embodiment, by providing a plurality of fluidized bed dryers, the reduction in the continuity of the drying of the granular material is alleviated. For example, as shown in FIG. 1, when the second fluidized bed dryer 40 is drying the granular material or discharging the granular material, and the first fluidized bed dryer 30 has already discharged the granular material, new granular material is supplied to the first fluidized bed dryer 30. Thereafter, as shown in FIG. 2, when the second fluidized bed dryer 40 has finished discharging the granular material, the indicating device 100 switches the state of the supply branch valve 22, so that new granular material is supplied to the second fluidized bed dryer 40.

[0032] As described above, since the granular material is continuously supplied from the pneumatic dryer 21 to the fluidized bed drying section 23, one of the first fluidized bed dryer 30 and the second fluidized bed dryer 40 is always in a state where it can supply the granular material (that is, a state where the drying and discharging of the previously supplied granular material are completed). In other words, while the granular material is being supplied to one of the first fluidized bed dryer 30 and the second fluidized bed dryer 40, the drying and discharging of the granular material are performed by the other. Since a predetermined amount of granular material is supplied to the first fluidized bed dryer 30 or the second fluidized bed dryer 40, the time required for drying and discharging is also constant. Therefore, the indicating device 100 switches the states of the supply branch valve 22 and the discharge branch valve 24 in accordance with a predetermined time schedule.

[0033] Here, if the pneumatic dryer 21 is omitted, the granular material with a large amount of moisture will be supplied to the fluidized bed drying section 23. In this case, the granular material is likely to adhere to the inner wall of the first fluidized bed dryer 30 or the second fluidized bed dryer 40. As a result, it is necessary to maintain the fluidized bed drying section 23 at a high frequency. In this regard, in this embodiment, the granular material with a reduced moisture content after passing through the pneumatic dryer 21 is supplied to the fluidized bed drying section 23. Therefore, since the granular material is less likely to adhere to the inner wall of the first fluidized bed dryer 30 or the second fluidized bed dryer 40, the frequency of maintenance can be reduced.

[0034] The collection section 70 includes a first collector 71, a first recovery container 72, a second collector 73, and a second recovery container 74.

[0035] The first collector 71 is a cyclone separator that separates the granular material and the high-temperature gas flowing in a combined state. The granular material separated by passing through the first collector 71 falls into the lower first recovery container 72 and is stored. Also, the high-temperature gas separated by passing through the first collector 71 flows toward the second collector 73. Note that the high-temperature gas flowing into the second collector 73 contains granular material (especially fine powder with a small diameter) that could not be separated by the first collector 71.

[0036] The second collector 73 is a filter separator called a bag filter or the like. The second collector 73 separates the remaining granular material from the high-temperature gas that has passed through the first collector 71. The granular material separated by passing through the second collector 73 is stored in the second recovery container 74. The high-temperature gas separated by passing through the second collector 73 is discharged by the suction section 60.

[0037] The air supply section 50 sends drying gas to the drying section 20. The air supply section 50 includes an air filter 51, an outside air adjustment valve 52, a blower fan 53, a heater 54, a first high-temperature gas adjustment valve 55, a second high-temperature gas adjustment valve 56, a third high-temperature gas adjustment valve 57, and a fourth high-temperature gas adjustment valve 58. In this embodiment, outside air is used as the drying air, but another gas may be used, or another gas may be mixed with the outside air.

[0038] The air filter 51 removes dust, dirt, etc. contained in the outside air. The outside air adjustment valve 52 can adjust the suction volume of the gas or the presence or absence of gas suction. The blower fan 53 sends the gas toward the drying section 20.

[0039] The gas sent out by the blower section 50 is heated by the heater 54 to become a first high-temperature gas. The high-temperature gas is sent to the pneumatic dryer 21 via the first high-temperature gas adjustment valve 55 and is also sent to the fluidized bed drying section 23 via the second high-temperature gas adjustment valve 56. In addition, the gas sent out by the blower section 50 is sent to the fluidized bed drying section 23 via a path that does not pass through the heater 54. That is, the fluidized bed drying section 23 is supplied with the gas (high-temperature gas) that has passed through the heater 54 and the gas (normal-temperature gas, outside air) that has not passed through the heater 54.

[0040] Generally, a gas at a relatively high temperature is used in the pneumatic dryer 21. On the other hand, in the fluidized bed drying section 23, a gas at a lower temperature than that in the pneumatic dryer 21 is used. If a high-output heater for heating the gas supplied to the pneumatic dryer 21 and a low-output heater for heating the gas supplied to the fluidized bed drying section 23 are provided, the cost of the heater will increase. In this regard, in the present embodiment, only the gas that has passed through the heater 54 is supplied to the pneumatic dryer 21, so a relatively high first high-temperature gas is supplied to the pneumatic dryer 21. On the other hand, since the fluidized bed drying section 23 is supplied with a second high-temperature gas obtained by mixing the first high-temperature gas that has passed through the heater 54 and the outside air that has not passed through the heater 54, a gas at a relatively low temperature is supplied. Thereby, a gas at an appropriate temperature can be supplied to the pneumatic dryer 21 and the fluidized bed drying section 23 without providing two heaters.

[0041] Note that by changing the opening degree of the second high-temperature gas adjustment valve 56, the mixing ratio of the high-temperature gas and the normal-temperature gas can be changed. For example, based on the detection result of a temperature sensor (not shown), by changing the opening degree of the second high-temperature gas adjustment valve 56, the temperature of the gas supplied to the fluidized bed drying section 23 can be stabilized.

[0042] The path for supplying gas to the fluidized bed drying section 23 branches into a first supply path for supplying gas to the first fluidized bed dryer 30 and a second supply path for supplying gas to the second fluidized bed dryer 40. The third high-temperature gas regulating valve 57 is provided in the first supply path and can switch whether to supply gas to the first fluidized bed dryer 30. The fourth high-temperature gas regulating valve 58 is provided in the second supply path and can switch whether to supply gas to the second fluidized bed dryer 40.

[0043] The suction section 60 generates a suction flow for sending the powder and granules or a suction flow for discharging the drying gas supplied to the fluidized bed drying section 23. The suction section 60 includes a sending suction fan 61, a suction flow regulating valve 62, an exhaust suction fan 63, a first exhaust valve 64, a second exhaust valve 65, and a third exhaust valve 66.

[0044] The sending suction fan 61 is connected to the second collector 73 via the suction flow regulating valve 62. The powder and granules are discharged from the fluidized bed drying section 23 by the suction flow generated by the sending suction fan 61. Also, the powder and granules and gas discharged from the fluidized bed drying section 23 are discharged from the first collector 71 and the second collector 73.

[0045] The exhaust suction fan 63 is connected to the fluidized bed drying section 23 via the first exhaust valve 64. Specifically, the path connected to the first exhaust valve 64 branches into a first exhaust path connected to the first fluidized bed dryer 30 and a second exhaust path connected to the second fluidized bed dryer 40. The second exhaust valve 65 is provided in the first exhaust path. The second exhaust valve 65 can switch whether to discharge the gas supplied to the first fluidized bed dryer 30. The third exhaust valve 66 is provided in the second exhaust path. The third exhaust valve 66 can switch whether to discharge the gas supplied to the second fluidized bed dryer 40.

[0046] While the granular material is being supplied to the first fluidized bed dryer 30, the supply branch valve 22 connects the pneumatic dryer 21 and the first supply section 31. Since the granular material is supplied while sucking air through the first supply section 31, the third high-temperature gas regulating valve 57 is closed. The second exhaust valve 65 is open to exhaust the supplied gas. While the granular material is being supplied to the second fluidized bed dryer 40, each valve corresponding to the second fluidized bed dryer 40 operates in the same manner.

[0047] While the granular material is being dried in the first fluidized bed dryer 30, the supply branch valve 22 does not connect the pneumatic dryer 21 and the first supply section 31. The third high-temperature gas regulating valve 57 is open to supply high-temperature gas through the third high-temperature gas regulating valve 57. The second exhaust valve 65 is open to exhaust the supplied gas. While the granular material is being dried in the second fluidized bed dryer 40, each valve corresponding to the second fluidized bed dryer 40 operates in the same manner.

[0048] While the granular material is being discharged from the first fluidized bed dryer 30, the discharge branch valve 24 connects the first discharge section 33 and the first collector 71. Since no air intake is performed from the first supply section 31, the third high-temperature gas regulating valve 57 is opened and air intake is performed through the third high-temperature gas regulating valve 57. Since the supplied gas is exhausted from the first discharge section 33, the second exhaust valve 65 is closed. While the granular material is being discharged from the second fluidized bed dryer 40, each valve corresponding to the second fluidized bed dryer 40 operates in the same manner.

[0049] When intake air is performed via the first supply unit 31 (or the second supply unit 41), and when intake air is performed via the third high-temperature gas control valve 57 (or the fourth high-temperature gas control valve 58), the flow rate of the supplied gas is different. Therefore, in the present embodiment, the third high-temperature gas control valve 57, the fourth high-temperature gas control valve 58, the suction flow control valve 62, and the first exhaust valve 64 are valves whose opening degrees can be adjusted. On the other hand, the second exhaust valve 65 and the third exhaust valve 66 are valves that can only be switched between fully open and fully closed. Instead of the configuration of the present embodiment, the second exhaust valve 65 and the third exhaust valve 66 may be valves whose opening degrees can be adjusted, and the third high-temperature gas control valve 57 and the fourth high-temperature gas control valve 58 may be valves that can only be switched between fully open and fully closed. Of course, all the valves may be valves whose opening degrees can be adjusted.

[0050] Next, with reference to FIG. 3, the drying system 1 of the second embodiment will be described. In the description of the second embodiment, the same or similar members as those in the first embodiment may be denoted by the same reference numerals in the drawings, and the description may be omitted.

[0051] The supply unit 10 of the first embodiment supplies the granular material to the drying unit 20, while the supply unit 10 of the second embodiment supplies the granulated product generated from the powder to the drying unit 20. Specifically, the supply unit 10 includes a powder supply unit 11 and a granulation unit 12. The powder supply unit 11 supplies the powder stored in the storage unit in the same manner as in the first embodiment. The granulation unit 12 stirs the powder supplied by the powder supply unit 11 to generate a granulated product. The granulation unit 12 continuously supplies the generated granulated product to the pneumatic dryer 21. In the first embodiment and the second embodiment, only the object to be dried is different, and the flow of the drying process is the same.

[0052] When drying the granulated product batchwise in a fluidized bed dryer, there is a possibility that the granulated products may integrate with each other while a predetermined amount of the granulated product is stored in the fluidized bed dryer. In this regard, in the present embodiment, the granulated product supplied by the supply unit 10 is continuously dried in the pneumatic dryer 21. Therefore, when the granulated product is stored in the first fluidized bed dryer 30 or the second fluidized bed dryer 40, since the moisture content of the granulated product has decreased, it is difficult for the granulated products to integrate with each other.

[0053] As described above, the drying system 1 of the above embodiment includes a pneumatic dryer 21, a fluidized bed drying unit 23, a supply branch valve 22, and a collection unit 70, and executes the following drying method. The pneumatic dryer 21 has a drying path 21a, and dries the granular material by flowing the granular material, which is the object to be dried, and a gas for drying the granular material through the drying path 21a (pneumatic drying step). The fluidized bed drying unit 23 is provided downstream of the pneumatic dryer 21, and has at least a first drying space 32 and a second drying space 42, and fluidizes and dries the granular material accommodated in the first drying space 32 or the second drying space 42 (fluidized bed drying step). The supply branch valve 22 is capable of switching between a state of supplying the granular material dried by the pneumatic dryer 21 to the first drying space 32 and a state of supplying the granular material dried by the pneumatic dryer 21 to the second drying space 42. The collection unit 70 collects the granular material dried in the first drying space 32 and the second drying space 42 (collection step).

[0054] Thereby, since the granular material dried by the pneumatic dryer 21 and having a reduced moisture content is supplied to the fluidized bed drying unit 23, it is difficult for the granular material to adhere to the inner wall of the fluidized bed drying unit 23. Further, in the pneumatic dryer 21, the flow velocity of the gas in the path is high and the concentration of the granular material with respect to the gas is low, so the surface of the granular material is quickly dried and it is difficult for the granular material to adhere to the inner wall of the path. As described above, in the drying system 1 of the present embodiment, the maintenance frequency of both the pneumatic dryer 21 and the fluidized bed drying unit 23 is reduced. Further, since there are a plurality of supply destinations for the granular material dried by the pneumatic dryer 21, the waiting time for the granular material can be made zero or short, so that the granular material can be continuously dried.

[0055] The drying system 1 of the above embodiment includes a discharge branch valve 24 that is capable of switching between a state of discharging the granular material dried in the first drying space 32 to the collection unit 70 and a state of discharging the granular material dried in the second drying space 42 to the collection unit 70.

[0056] Thereby, the granular materials dried in the two drying spaces can be collected and recovered at one location.

[0057] The drying system 1 of the above embodiment includes at least an instruction device 100 that operates the supply branch valve 22. The instruction device 100 switches the state of the supply branch valve 22 so that the granular material is supplied to the first drying space 32 after the drying and discharging of the granular material are completed in the first drying space 32, and so that the granular material is supplied to the second drying space 42 after the drying and discharging of the granular material are completed in the second drying space 42.

[0058] Thereby, the granular material can be supplied to the first drying space 32 or the second drying space 42 at an appropriate timing.

[0059] In the drying system 1 of the above embodiment, the granular material is a granulated product produced by the granulation unit 12, and the granulated product produced by the granulation unit 12 is continuously supplied to the pneumatic dryer 21.

[0060] Thereby, since the granulated product containing a large amount of moisture is continuously dried, it is possible to prevent the granulated products from integrating with each other.

[0061] The drying system 1 of the present embodiment includes a heater 54 that heats the gas supplied to the pneumatic dryer 21 and the fluidized bed drying unit 23. The first high-temperature gas heated by the heater 54 is supplied to the pneumatic dryer 21, and the second high-temperature gas whose temperature is lowered by mixing outside air with the first high-temperature gas is supplied to the fluidized bed drying unit 23.

[0062] Thereby, compared with a configuration in which individual heaters are provided for the pneumatic dryer 21 and the fluidized bed drying unit 23, the number of heaters can be reduced.

[0063] Although the preferred embodiments of the present invention have been described above, the above configuration can be modified as follows, for example.

[0064] In the above-described embodiment, the instruction device 100 switches the supply branch valve 22, the discharge branch valve 24, etc. in accordance with a predetermined time schedule. Alternatively, a sensor for measuring the progress of drying and discharging in the first fluidized bed dryer 30 or the second fluidized bed dryer 40 may be provided, and the supply branch valve 22, the discharge branch valve 24, etc. may be switched based on the detection result of the sensor.

[0065] In the above-described embodiment, the collection unit 70 includes the first collector 71 and the second collector 73. However, for example, the first collector 71 may be omitted from the collection unit 70.

Explanation of Reference Numerals

[0066] 1 Drying system 10 Supply unit 20 Drying unit 21 Pneumatic dryer 22 Supply branch valve (supply switching unit) 23 Fluidized bed drying section 24 Discharge branch valve (discharge switching unit) 30 First fluidized bed dryer 32 First drying space 40 Second fluidized bed dryer 42 Second drying space 50 Blower unit 60 Suction unit 70 Collection unit

Claims

1. An air current dryer having a drying path, wherein the particulate matter to be dried and a gas for drying the particulate matter are passed through the drying path to dry the particulate matter; A fluidized bed drying section provided downstream of the air current dryer and having at least a first drying space and a second drying space, for fluidizing and drying the particulate matter accommodated in the first drying space or the second drying space; A supply switching section capable of switching between a state of supplying the particulate matter dried by the air current dryer to the first drying space and a state of supplying the particulate matter dried by the air current dryer to the second drying space; A collection section for collecting the particulate matter dried in the first drying space and the second drying space; A first supply section including a path for supplying the particulate matter to the first drying space; A second supply section including a path for supplying the particulate matter to the second drying space; comprising; When supplying the particulate matter to the first drying space, intake air is drawn into the first drying space through the first supply section; When supplying the particulate matter to the second drying space, intake air is drawn into the second drying space through the second supply section; When drying the particulate matter in the first drying space, intake air is drawn into the first drying space through a first intake path different from the first supply section; When drying the particulate matter in the second drying space, intake air is drawn into the second drying space through a second intake path which is different from the second supply section and partially common with the first intake path. A drying system characterized by this.

2. An air current dryer having a drying path, wherein the particulate matter to be dried and a gas for drying the particulate matter are passed through the drying path to dry the particulate matter; A fluidized bed drying section provided downstream of the air current dryer and having at least a first drying space and a second drying space, for fluidizing and drying the particulate matter accommodated in the first drying space or the second drying space; A supply switching unit capable of switching between a state of supplying the granular material dried by the pneumatic dryer to the first drying space and a state of supplying the granular material dried by the pneumatic dryer to the second drying space; A collecting unit that collects the granular material dried in the first drying space and the second drying space; A heater that heats the gas supplied to the pneumatic dryer and the fluidized bed drying unit; Comprising A first high-temperature gas heated by the heater is supplied to the pneumatic dryer, and a second high-temperature gas with the temperature reduced by mixing outside air with the first high-temperature gas is supplied to the fluidized bed drying unit. A drying system characterized by this.

3. The drying system according to claim 1 or 2, Comprising a discharge switching unit capable of switching between a state of discharging the granular material dried in the first drying space to the collecting unit and a state of discharging the granular material dried in the second drying space to the collecting unit. A drying system characterized by this.

4. The drying system according to any one of claims 1 to 3, Comprising an instruction device for operating at least the supply switching unit, The instruction device switches the state of the supply switching unit so that the granular material is supplied to the first drying space after drying and discharging of the granular material in the first drying space are completed, and so that the granular material is supplied to the second drying space after drying and discharging of the granular material in the second drying space are completed. A drying system characterized by this.

5. The drying system according to any one of claims 1 to 4, The granular material is a granulated product produced by a granulation unit, and the granulated product produced by the granulation unit is continuously supplied to the pneumatic dryer. A drying system characterized by this.

6. An airflow drying step of drying the granular material by flowing the granular material, which is an object to be dried, and a gas for drying the granular material through a drying path; Supply the granular material that has undergone the pneumatic drying process to the first drying space or the second drying space, and perform a fluidized bed drying process of fluidizing and drying the granular material accommodated in the first drying space or the second drying space; A collecting step of collecting the granular material dried in the first drying space and the second drying space; including It is possible to switch between a state of supplying the granular material dried in the pneumatic drying process to the first drying space and a state of supplying the granular material dried in the pneumatic drying process to the second drying space, When supplying the granular material to the first drying space, intake air is introduced into the first drying space through a first supply unit including a path for supplying the granular material; When supplying the granular material to the second drying space, intake air is introduced into the second drying space through a second supply unit including a path for supplying the granular material; When drying the granular material in the first drying space, intake air is introduced into the first drying space through a first intake path different from the first supply unit; A drying method characterized in that when drying the granular material in the second drying space, intake air is introduced into the second drying space through a second intake path that is different from the second supply unit and partially common with the first intake path.

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