JP7736466B2 - Drying system and drying method - Google Patents

Description

The present invention primarily relates to a drying system for drying powdered or granular materials.

Patent Document 1 discloses a fluidized bed dryer that continuously dries powder and granular materials. The fluidized bed dryer has multiple processing chambers separated by partitions. Powder and granular materials are sequentially introduced into each processing chamber, and the powder and granular materials that have been dried are sequentially discharged.

Patent Document 2 discloses a drying device in which a flash dryer is installed above a fluidized bed dryer. The material dried by the flash dryer is further dried by the fluidized bed dryer.

Patent Document 3 discloses an apparatus equipped with a flash drying tube and a dryer. Hot air flows through the flash drying tube, and the material to be dried is dried by flowing it through the flash drying tube. After primary drying in the flash drying tube, the material to be dried is then placed in the dryer. In the dryer, the material is dried by flowing it in a superheated steam atmosphere.

Japanese Patent Application Laid-Open No. 2016-125697 Japanese Utility Model Application Publication No. 61-60088 JP 2009-133591 A

In the fluidized bed dryer of Patent Document 1, powder with a high moisture content is supplied to the treatment chamber, which means that the powder easily adheres to the inner walls of the treatment chamber. This requires frequent maintenance to clean the inner walls of the treatment chamber. In the devices of Patent Documents 2 and 3, when materials to be dried are continuously supplied to the fluidized bed dryer/drying chamber, uneven drying of the materials may occur, potentially resulting in insufficient drying.

The present invention was made in consideration of the above circumstances, and its main purpose is to provide a drying system that requires less maintenance and is capable of properly drying powder and granular materials.

The problem that this invention aims to solve is as described above. Next, we will explain the means for solving this problem and its effects.

According to a first aspect of the present invention, there is provided a drying system having the following configuration. Specifically, the drying system includes a flash dryer, a storage unit, a fluidized bed dryer, and a supply switching unit. The flash dryer has a drying path and dries the powder or granules by flowing the powder or granules to be dried and a gas for drying the powder or granules through the drying path. The storage unit temporarily stores the powder or granules dried by the flash dryer. The fluidized bed dryer is located downstream of the flash dryer and has a drying space, and fluidizes and dries the powder or granules contained in the drying space. The supply switching unit is switchable between a closed state in which the powder or granules are maintained in storage without being supplied to the fluidized bed dryer by closing the path connecting the storage unit to the fluidized bed dryer, and a supply state in which the powder or granules stored in the storage unit are supplied to the fluidized bed dryer.

According to a second aspect of the present invention, the following drying method is provided. Specifically, the drying method includes an airflow drying process, a storage process, a supply process, and a fluidized bed drying process. In the airflow drying process, the powder or granule to be dried and a gas for drying the powder or granule are caused to flow through a drying path formed in the airflow dryer, thereby drying the powder or granule. In the storage process, the powder or granule dried in the airflow drying process is stored in a storage section. In the supply process, the powder or granule stored in the storage section is supplied to a fluidized bed dryer. In the fluidized bed drying process, the powder or granule contained in the drying space is fluidized and dried using a fluidized bed dryer having a drying space.

As a result, the powder and granules, which have been dried in the flash dryer and have a reduced moisture content, are supplied to the fluidized bed dryer, making it less likely for the powder and granules to adhere to the inner walls of the fluidized bed dryer. Furthermore, in the flash dryer, the gas flow rate within the passage is fast and the powder and granule concentration relative to the gas is low, so the surface of the powder and granules dries quickly and the powder and granules are less likely to adhere to the inner walls of the passage. As a result, the above drying system requires less frequent maintenance for both the flash dryer and the fluidized bed dryer. Furthermore, because the powder and granules dried in the flash dryer are collected and supplied to the fluidized bed dryer, the powder and granules can be dried uniformly, ensuring proper drying.

The present invention provides a drying system that requires less frequent maintenance and is capable of properly drying powder and granular materials.

FIG. 2 is a diagram showing a state during drying in a fluidized bed dryer in the drying system of the first embodiment. FIG. 2 is a diagram showing a state in which powder and granular material dried in a fluidized bed dryer is discharged in the drying system of the first embodiment. FIG. 2 is a diagram showing a state in which new powder or granular material is supplied to the fluidized bed dryer in the drying system of the first embodiment. 10 is a flowchart showing a process performed by the instruction device. FIG. 10 is a diagram showing the configuration of a drying system according to a second embodiment. FIG. 10 is a diagram showing the configuration of a drying system according to a third embodiment.

Next, embodiments of the present invention will be described with reference to the drawings. First, a drying system 1 according to a first embodiment will be described with reference to Figures 1 to 3.

The drying system 1 is configured to include multiple devices for drying powdered or granular materials. "Powdered or granular materials" is a term that refers to powders, granules (including granulated products), and mixtures of powders and granules. Powdered or granular materials may be pharmaceuticals or foods, or may be other substances. In the following description, the upstream/downstream of the flow of powdered or granular materials or gas may be simply referred to as upstream/downstream.

As shown in FIG. 1, the drying system 1 includes a supply unit 10, a drying unit 20, a blower unit 30, and an exhaust processing unit 40.

The supply unit 10 supplies powder or granular material to be dried to the drying unit 20. The powder or granular material supplied by the supply unit 10 contains a large amount of moisture. The supply unit 10 comprises a portion for storing the powder or granular material and a portion for continuously delivering the powder or granular material. With this configuration, the supply unit 10 continuously supplies the powder or granular material to the drying unit 20.

The drying section 20 dries the powder or granular material supplied by the supply section 10. The drying section 20 includes a flash dryer 21, a first collector 22, a storage section 23, a supply switching section 24, a fluidized bed dryer 25, a discharge switching section 26, and a first collection container 27.

The flash dryer 21 has a housing within which a drying path 21a is formed. The drying path 21a is a long, narrow path that includes curved, arc-shaped, or folded-back sections to increase the path length. Powder and granular material supplied by the supply unit 10 flows through the drying path 21a. High-temperature gas supplied by the air blower unit 30 (details described below) also flows through the drying path 21a. As a result, the powder and granular material flows through the drying path 21a together with the high-temperature gas, causing the powder and granular material to dry (primary drying).

The first collector 22 is a cyclone-type separator that separates the powder and granular material from the high-temperature gas that flow together. The powder and granular material that has been separated by passing through the first collector 22 falls into the storage section 23 below and is stored there. The high-temperature gas that has been separated by passing through the first collector 22 is discharged to the outside by the discharge processing section 40 (details of which will be described later).

The storage section 23 is a hopper-shaped container in which the powder and granular material separated by the first collector 22 is temporarily stored. A supply hole for supplying the powder and granular material is formed in the lower part of the storage section 23, and the supply hole of the storage section 23 is configured to be closable by the supply switching section 24. The storage section 23 is not limited to a hopper-shaped container, and may be a container of any suitable shape that can discharge granular material.

A supply switching unit 24 is disposed below the storage unit 23. The supply switching unit 24 can switch between a closed state (Figures 1 and 2) in which the powder and granular material stored in the storage unit 23 is maintained without being supplied to the fluidized bed dryer 25 by closing the supply hole of the storage unit 23, and a supply state (Figure 3) in which the powder and granular material stored in the storage unit 23 is supplied to the fluidized bed dryer 25 by opening the supply hole of the storage unit 23.

The operation of the supply switching unit 24 is controlled by the indicator 100. The indicator 100 includes a CPU, ROM, RAM, etc. The indicator 100 can control the drying system 1 by reading a program stored in the ROM into the RAM and executing it. In this embodiment, the supply switching unit 24 is operated by an actuator such as a motor or cylinder. The indicator 100 can switch the supply switching unit 24 between a closed state and a supply state by issuing an instruction to this actuator.

A fluidized bed dryer 25 is located below the supply switching unit 24. The fluidized bed dryer 25 performs secondary drying to further dry the powder and granules that have been primarily dried by the flash dryer 21. The fluidized bed dryer 25 has a drying space where secondary drying is performed. The fluidized bed dryer 25 is container-shaped, and its interior is the drying space. High-temperature gas is supplied to the fluidized bed dryer 25 by the air blower 30. The high-temperature gas is supplied from the bottom to the upward direction of the drying space of the fluidized bed dryer 25. This causes the powder and granules to flow within the drying space, allowing the powder and granules to be dried.

The ratio of the amount of moisture removed in primary drying to the amount removed in secondary drying is not particularly limited, but in this embodiment, the amount of moisture removed in primary drying is greater than the amount of moisture removed in secondary drying. This is because it becomes more difficult to remove moisture as the moisture content of the powder or granule decreases. However, the amount of moisture removed in primary drying may be less than the amount of moisture removed in secondary drying.

After secondary drying in the fluidized bed dryer 25, the powder or granules are discharged into the first collection container 27 below. Specifically, a discharge hole (path) is formed in the bottom of the fluidized bed dryer 25 for discharging the powder or granules downward. The discharge hole of the fluidized bed dryer 25 is closed by the discharge switching unit 26. Specifically, the discharge switching unit 26 can switch between a closed state (FIGS. 1 and 3) in which the discharge hole is closed and no powder or granules are discharged, and a discharge state (FIG. 2) in which the discharge hole is open and the dried powder or granules in the fluidized bed dryer 25 are discharged into the first collection container 27. The operation of the discharge switching unit 26 is controlled by the indicator 100. Note that instead of the first collection container 27, a transport device (conveyor or suction device) for sending the powder or granules to the next process may be provided.

Here, the flash dryer 21 is a continuous drying device. A continuous system is one in which powder or granular material is continuously supplied, dried as it is sent out without being stored, and then the powder or granular material is discharged.

In contrast, the fluidized bed dryer 25 is a batch type. A batch type is a method in which a predetermined amount is defined as one unit and one unit of powder or granules is dried at once. Therefore, a predetermined amount of powder or granules is first supplied to the fluidized bed dryer 25, and drying begins after the supply of the powder or granules is completed. Then, after drying is completed, all of the powder or granules supplied to the fluidized bed dryer 25 (i.e., the predetermined amount) are discharged together into the first collection container 27.

In other words, while the flash dryer 21 continuously discharges powder and granular material, the fluidized bed dryer 25 is not configured to continuously dry the powder and granular material. Furthermore, if powder and granular material were continuously supplied to the fluidized bed dryer, powder and granular material with different degrees of dryness would be mixed, resulting in uneven drying, which is undesirable.

In this regard, in this embodiment, by providing a storage section 23, continuously supplied powder and granules can be temporarily stored. Furthermore, because this powder and granules have undergone primary drying, they are less likely to merge together. After a predetermined amount of powder and granules has been stored in the storage section 23, they are supplied to the fluidized bed dryer 25. This allows for both continuous drying and batch drying. Furthermore, because this powder and granules have undergone primary drying, they are less likely to adhere to the inner walls of the fluidized bed dryer 25. This reduces the frequency of maintenance.

As described above, powder and granular material are continuously supplied from the flash dryer 21 to the storage section 23, and the amount of powder and granular material supplied to the storage section 23 per unit time is constant. Furthermore, the above-mentioned unit of secondary drying performed in the fluidized bed dryer 25 is constant. Therefore, the indicating device 100 of this embodiment switches the state of the supply switching unit 24 in accordance with a predetermined time schedule. Furthermore, the time for which secondary drying is performed in the fluidized bed dryer 25 is also constant. Therefore, the indicating device 100 switches the state of the discharge switching unit 26 in accordance with a predetermined time schedule.

The blower unit 30 sends out drying gas to the drying unit 20. The blower unit 30 includes an air filter 31, an outside air adjustment valve 32, a blower fan 33, a heater 34, a first high-temperature gas adjustment valve 35, a second high-temperature gas adjustment valve 36, a third high-temperature gas adjustment valve 37, and a fourth high-temperature gas adjustment valve 38. In this embodiment, outside air is used as the drying air, but another gas may also be used, or another gas may be mixed with outside air.

The air filter 31 removes dust and other particles from the outside air. The outside air adjustment valve 32 can adjust the amount of gas sucked in or whether or not gas is sucked in. The blower fan 33 sends the gas toward the drying section 20.

The gas sent out by the blower 30 is heated by the heater 34 to become a first high-temperature gas. The high-temperature gas is sent to the flash dryer 21 via the first high-temperature gas regulating valve 35 and to the fluidized bed dryer 25 via the second high-temperature gas regulating valve 36. The gas sent out by the blower 30 is also sent to the fluidized bed dryer 25 via a path that does not pass through the heater 34. In other words, the fluidized bed dryer 25 is supplied with gas that has passed through the heater 34 (high-temperature gas) and gas that has not passed through the heater 34 (room-temperature gas, outside air).

Generally, gas at a relatively high temperature is used in the flash dryer 21. In contrast, gas at a lower temperature than that used in the fluidized bed dryer 25 is used in the flash dryer 21. If a high-output heater were provided to heat the gas supplied to the flash dryer 21 and a low-output heater were provided to heat the gas supplied to the fluidized bed dryer 25, the cost of the heaters would be high. In this regard, in this embodiment, only gas that has passed through the heater 34 is supplied to the flash dryer 21, so a relatively high first high-temperature gas is supplied to the flash dryer 21. On the other hand, a second high-temperature gas that is a mixture of the first high-temperature gas that has passed through the heater 34 and outside air that has not passed through the heater 34 is supplied to the fluidized bed dryer 25, so gas at a relatively low temperature is supplied. This makes it possible to supply gas at appropriate temperatures to the flash dryer 21 and the fluidized bed dryer 25 without providing two heaters.

The mixture ratio of high-temperature gas and room-temperature gas can be changed by changing the aperture of the second high-temperature gas regulating valve 36. For example, the temperature of the gas supplied to the fluidized bed dryer 25 can be stabilized by changing the aperture of the second high-temperature gas regulating valve 36 based on the detection results of a temperature sensor (not shown).

The path that supplies the second high-temperature gas to the fluidized bed dryer 25 is branched. One of the branched paths, supply path 61, is connected to the fluidized bed dryer 25. The other branched path, bypass path 62, is connected to the discharge treatment unit 40 without passing through the fluidized bed dryer 25. The second high-temperature gas supplied to the fluidized bed dryer 25 is discharged to the discharge treatment unit 40 via a filter and discharge path 63.

A third high-temperature gas regulating valve 37 is provided in the supply path 61. The flow rate of the second high-temperature gas supplied to the fluidized bed dryer 25 can be adjusted by changing the aperture of the third high-temperature gas regulating valve 37. Note that the second high-temperature gas cannot be supplied to the fluidized bed dryer 25 by closing the third high-temperature gas regulating valve 37. A fourth high-temperature gas regulating valve 38 is provided in the bypass path 62. The flow rate of the second high-temperature gas flowing through the bypass path 62 can be adjusted by changing the aperture of the fourth high-temperature gas regulating valve 38. This makes it possible to make the flow rate of the second high-temperature gas when it flows into the fluidized bed dryer 25 the same as when it flows through the bypass path 62.

The discharge treatment unit 40 generates a suction flow to move powder and granular materials and discharge high-temperature gas. The discharge treatment unit 40 includes a suction fan 41, an exhaust adjustment valve 42, a second collector 43, a second collection container 44, and an exhaust switching valve 45.

The suction fan 41 generates a suction flow. The functions of the suction flow generated by the suction fan 41 are to transport the powder and granular material, to generate a swirling flow that separates the high-temperature gas from the powder and granular material in the first collector 22, and to exhaust the second high-temperature gas supplied to the fluidized bed dryer 25. The suction fan 41 is connected to the second collector 43 via the exhaust adjustment valve 42. The strength of the suction flow can be adjusted by changing the opening of the exhaust adjustment valve 42.

The second collector 43 is a filter-type separator known as a bag filter or the like. The second collector 43 is connected downstream of the first collector 22 in the flow direction of the high-temperature gas. The second collector 43 separates powder and granular material contained in the high-temperature gas that was not separated by the first collector 22. The powder and granular material separated by passing through the second collector 43 is stored in the second collection container 44. The high-temperature gas separated by passing through the second collector 43 is discharged by the discharge treatment unit 40.

The second collector 43 is connected to the exhaust switching valve 45 via the suction path 64. The exhaust switching valve 45 is a three-way valve connected to the suction path 64, the supply path 61, and the bypass path 62. The exhaust switching valve 45 is configured to be switchable between a state in which the suction path 64 and the supply path 61 are connected (exhaust state, Figure 1) and a state in which the suction path 64 and the bypass path 62 are connected (closed state, Figures 2 and 3). When the exhaust switching valve 45 connects the suction path 64 and the exhaust path 63, the second high-temperature gas supplied to the fluidized bed dryer 25 is discharged to the discharge treatment unit 40. When the exhaust switching valve 45 connects the suction path 64 and the bypass path 62, the path connecting the fluidized bed dryer 25 and the suction fan 41 is closed, and the second high-temperature gas supplied to the bypass path 62 is discharged to the discharge treatment unit 40.

Next, with further reference to Figure 4, the process flow for drying powder and granular materials will be explained.

First, the instruction device 100 closes the supply switching unit 24, closes the exhaust switching unit 26, connects the bypass path 62 and the suction path 64 to the exhaust switching valve 45, and closes the exhaust switching valve 45 (S101). The instruction device 100 then starts the supply of powder and granular material by the supply unit 10, and starts primary drying of the powder and granular material by the flash dryer 21 (S101).

Next, the indicating device 100 switches the supply switching unit 24 from the closed state to the supply state, and supplies the powder or granular material to the fluidized bed dryer 25 (S102, Figure 3). At this time, because the discharge switching unit 26 is in the closed state, the supplied powder or granular material does not fall from the fluidized bed dryer 25 into the first collection container 27. Furthermore, because the exhaust switching valve 45 is in the closed state, no gas flow is generated from the fluidized bed dryer 25 toward the discharge processing unit 40, so the supplied powder or granular material can be properly deposited in the fluidized bed dryer 25.

Next, after the time (supply time) required to supply a predetermined amount of powder or granular material to the fluidized bed dryer 25 has elapsed, the indicating device 100 switches the supply switching unit 24 from the supply state to the closed state (S103). This switches the state from one in which powder or granular material is supplied to the fluidized bed dryer 25 to one in which powder or granular material is stored in the storage unit 23.

Next, the indicator 100 connects the exhaust path 63 and the suction path 64 to the exhaust switching valve 45, placing the exhaust switching valve 45 in the exhaust state (S104). This causes the second high-temperature gas to be supplied to the fluidized bed dryer 25, and secondary drying by the fluidized bed dryer 25 begins (S104, Figure 1).

Next, after the drying time has elapsed, the indicating device 100 connects the bypass path 62 and the suction path 64 to the exhaust switching valve 45, closing the exhaust switching valve 45 (S105). As a result, the second high-temperature gas flows to the exhaust processing unit 40 without being supplied to the fluidized bed dryer 25.

Next, the indicating device 100 switches the discharge switching unit 26 from the closed state to the discharge state, and discharges the powder or granular material into the first collection container 27 (S106, Figure 2). At this time, because the exhaust switching valve 45 is in the closed state, no gas flow is generated from the fluidized bed dryer 25 toward the discharge processing unit 40, so the movement of the powder or granular material being discharged into the first collection container 27 is suppressed, and the powder or granular material can be appropriately discharged into the first collection container 27.

Next, after the discharge time has elapsed, the indicating device 100 switches the discharge switching unit 26 from the discharge state to the closed state (S107). The indicating device 100 then performs steps S102 to S107 again. As a result, the powder and granular material continuously supplied from the flash dryer 21 can be dried in the batch-type fluidized bed dryer 25.

Next, a second embodiment of the drying system 1 will be described with reference to Figure 5. Note that in the second and subsequent descriptions, components that are the same as or similar to those in the first embodiment will be designated by the same reference numerals in the drawings, and descriptions thereof may be omitted.

While the supply unit 10 in the first embodiment supplies powder to the drying unit 20, the supply unit 10 in the second embodiment supplies granulated material (a type of powder) produced from powder to the drying unit 20. Specifically, the supply unit 10 includes a powder supply unit 11 and a granulation unit 12. As in the first embodiment, the powder supply unit 11 supplies powder stored in a storage unit. The granulation unit 12 generates granulated material by stirring the powder supplied by the powder supply unit 11, etc. The granulation unit 12 continuously supplies the generated granulated material to the flash dryer 21. The first and second embodiments differ only in the object to be dried, and the drying process flow is the same.

When drying granulated material in a batch-type fluidized bed dryer, there is a possibility that the granulated material may become integrated with other granulated material while it is being stored in the storage section 23. In this embodiment, the granulated material supplied by the supply section 10 is continuously dried in the flash dryer 21. Therefore, by the time the granulated material is stored in the storage section 23, its moisture content has decreased, making it less likely for the granulated material to become integrated with other granulated material.

Next, the drying system 1 of the third embodiment will be described with reference to Figure 6.

The drying system 1 of the first embodiment is configured to include one storage section 23 and one fluidized bed dryer 25. Instead, the drying system 1 of the third embodiment includes two sets of devices related to secondary drying (hereinafter, secondary drying devices 28). The secondary drying device 28 includes a first collector 22, a storage section 23, a supply switching section 24, a fluidized bed dryer 25, a discharge switching section 26, a first collection container 27, a third high-temperature gas adjustment valve 37, and a fourth high-temperature gas adjustment valve 38.

The drying system 1 further includes a drying destination switching unit 29. The drying destination switching unit 29 is located downstream of the flash dryer 21 and upstream of the first collector 22. The drying destination switching unit 29 can switch between sending the granulated material dried by the flash dryer 21 to one first collector 22 and sending it to the other first collector 22. The operation of the drying destination switching unit 29 is controlled by the indicator device 100.

By providing two sets of secondary drying devices 28, powdered material can be supplied to one secondary drying device 28 while secondary drying is being performed in the other secondary drying device 28. Therefore, for example, in cases where the drying time of the fluidized bed dryer 25 is relatively long, it is preferable to adopt the drying system 1 of the third embodiment.

As described above, the drying system 1 of this embodiment includes the flash dryer 21, the storage unit 23, the fluidized bed dryer 25, and the supply switching unit 24, and performs the following drying method. The flash dryer 21 has a drying path 21a, and dries the powder or granules to be dried by flowing the powder or granules and a gas for drying the powder or granules through the drying path 21a (flash drying process). The storage unit 23 temporarily stores the powder or granules dried by the flash dryer 21 (storage process). The fluidized bed dryer 25 is located downstream of the flash dryer 21 and has a drying space. The powder or granules stored in the drying space are fluidized and dried (fluidized bed drying process). The supply switching unit 24 can switch between a closed state in which the powder and granular material is maintained in storage without being supplied to the fluidized bed dryer 25 by closing the path connecting the storage unit 23 to the fluidized bed dryer 25, and a supply state in which the powder and granular material stored in the storage unit 23 is supplied to the fluidized bed dryer 25; by switching to the supply state, the powder and granular material is supplied (supply process).

As a result, the powder and granules, which have been dried in the flash dryer 21 and have a reduced moisture content, are supplied to the fluidized bed dryer 25, making it less likely for the powder and granules to adhere to the inner walls of the fluidized bed dryer 25. Furthermore, in the flash dryer 21, the gas flow rate within the passage is fast and the powder and granules are less concentrated relative to the gas, so the surface of the powder and granules dries quickly and the powder and granules are less likely to adhere to the inner walls of the passage. As a result, the drying system 1 of this embodiment requires less frequent maintenance for both the flash dryer 21 and the fluidized bed dryer 25. Furthermore, because the powder and granules dried in the flash dryer 21 are collected and supplied to the fluidized bed dryer 25, the powder and granules can be dried uniformly and appropriately.

In the drying system 1 of this embodiment, the fluidized bed dryer 25 is located below the storage section 23.

This allows the powder to be supplied from the storage section 23 to the fluidized bed dryer 25 using gravity.

The drying system 1 of this embodiment includes a suction fan 41, an exhaust switching valve 45, and an indicating device 100. The suction fan 41 generates a suction flow. The exhaust switching valve 45 is capable of switching between an exhaust state in which the suction flow acts on the fluidized bed dryer 25 to exhaust gas for drying powder and granular material, and a closed state in which the path connecting the suction fan 41 and the fluidized bed dryer 25 is closed to prevent the suction flow from acting on the fluidized bed dryer 25. The indicating device 100 operates the supply switching unit 24 and the exhaust switching valve 45. After the exhaust switching valve 45 switches from the exhaust state to the closed state, the indicating device 100 switches the supply switching unit 24 from the closed state to the supply state.

As a result, no suction flow acts on the fluidized bed dryer 25 while the powder or granular material is being supplied from the storage section 23 to the fluidized bed dryer 25, allowing the powder or granular material to be supplied appropriately.

The drying system 1 of this embodiment is equipped with a discharge switching unit 26 that can switch between a closed state in which the path (discharge hole) for discharging powder or granular material from the fluidized bed dryer 25 is closed, and a discharge state in which the path for discharging powder or granular material from the fluidized bed dryer 25 is opened. After the exhaust switching valve 45 has switched from the exhaust state to the closed state and the discharge switching unit 26 has switched from the discharge state to the closed state, the indicating device 100 switches the supply switching unit 24 from the closed state to the supply state so that new powder or granular material is supplied to the fluidized bed dryer 25.

This allows new powder to be supplied to the fluidized bed dryer 25 after the dried powder is discharged.

In the drying system 1 of this embodiment, the powder is a granulated material produced by a granulating device, and the granulated material produced by the granulating device is continuously sent to the flash dryer 21.

This allows the granulated material, which contains a lot of moisture, to be dried continuously, preventing the granulated material from clumping together.

The drying system 1 of this embodiment includes a heater 34 that heats the air supplied to the flash dryer 21 and the fluidized bed dryer 25. The first high-temperature gas heated by the heater 34 is supplied to the flash dryer 21, and the second high-temperature gas, whose temperature has been lowered by mixing the first high-temperature gas with outside air, is supplied to the fluidized bed dryer 25.

This allows for a reduction in the number of heaters compared to a configuration in which separate heaters are provided for the flash dryer 21 and the fluidized bed dryer 25.

The above describes a preferred embodiment of the present invention, but the above configuration can be modified, for example, as follows:

In the above embodiment, the indicator device 100 switches the supply switching unit 24, discharge switching unit 26, exhaust switching valve 45, etc. according to a predetermined time schedule. Alternatively, a sensor may be provided to measure the progress of drying and discharge in the fluidized bed dryer 25, and the supply switching unit 24, discharge switching unit 26, exhaust switching valve 45, etc. may be switched based on the detection results of the sensor.

In the above embodiment, the first collector 22, storage section 23, and fluidized bed dryer 25 are arranged vertically, but they may be positioned in a different manner. That is, the powder and granular material may not only be moved by free fall due to gravity, but may also be moved using a conveyor, suction flow, etc.

The flowchart shown in the above embodiment is an example, and some processes may be omitted, the content of some processes may be changed, or new processes may be added.

1 Drying system 20 Drying section 21 Flash dryer 23 Storage section 24 Supply switching section 25 Fluidized bed dryer

Claims (6)

an air current dryer having a drying path, which dries powder or granular material to be dried by flowing a gas for drying the powder or granular material through the drying path;
a storage section for temporarily storing the powder or granular material dried by the flash dryer;
a fluidized bed dryer that is provided downstream of the flash dryer, has a drying space, and fluidizes and dries the powder or granular material contained in the drying space;
a supply switching unit that can switch between a closed state in which the powder or granular material is maintained in storage without being supplied to the fluidized bed dryer by closing a path connecting the storage unit to the fluidized bed dryer, and a supply state in which the powder or granular material stored in the storage unit is supplied to the fluidized bed dryer;
a discharge switching unit that can switch between a closed state in which a path for discharging the powder or granular material from the fluidized bed dryer is closed and a discharge state in which the path for discharging the powder or granular material from the fluidized bed dryer is opened;
a suction fan that generates a suction flow;
an exhaust switching valve capable of switching between an exhaust state in which the suction flow acts on the fluidized bed dryer to discharge a gas for drying the powder or granular material, and a closed state in which the path connecting the suction fan and the fluidized bed dryer is closed to prevent the suction flow from acting on the fluidized bed dryer;
an instruction device that operates the supply switching unit and the exhaust switching valve;
Equipped with
The drying system according to claim 1, wherein the indicator device switches the supply switching unit from the closed state to the supply state after the exhaust switching valve switches from the exhaust state to the closed state. an air current dryer having a drying path, which dries powder or granular material to be dried by flowing a gas for drying the powder or granular material through the drying path;
a storage section for temporarily storing the powder or granular material dried by the flash dryer;
a fluidized bed dryer that is provided downstream of the flash dryer, has a drying space, and fluidizes and dries the powder or granular material contained in the drying space;
a supply switching unit that can switch between a closed state in which the powder or granular material is maintained in storage without being supplied to the fluidized bed dryer by closing a path connecting the storage unit to the fluidized bed dryer, and a supply state in which the powder or granular material stored in the storage unit is supplied to the fluidized bed dryer;
a discharge switching unit that can switch between a closed state in which a path for discharging the powder or granular material from the fluidized bed dryer is closed and a discharge state in which the path for discharging the powder or granular material from the fluidized bed dryer is opened;
a heater for heating air to be supplied to the flash dryer and the fluidized bed dryer;
Equipped with
A drying system characterized in that a first high-temperature gas heated by the heater is supplied to the flash dryer, and a second high-temperature gas whose temperature is lowered by mixing the first high-temperature gas with outside air is supplied to the fluidized bed dryer. 3. The drying system of claim 1 or 2,
A drying system characterized in that the fluidized bed dryer is located below the storage section. 10. The drying system of claim 1 ,
The drying system is characterized in that the indicator device switches the supply switching unit from the closed state to the supply state so that new powder or granular material is supplied to the fluidized bed dryer after the exhaust switching valve has switched from the exhaust state to the closed state and after the exhaust switching unit has switched from the exhaust state to the closed state. 5. A drying system according to any one of claims 1 to 4, comprising:
The powder and granules are granulated material produced by a granulation device, and the granulated material produced by the granulation device is continuously sent to the flash dryer. an airflow drying step of drying the powder or granular material by flowing the powder or granular material to be dried and a gas for drying the powder or granular material through a drying path formed in the airflow dryer;
a storing step of storing the powder or granular material dried in the air flow drying step in a storing section;
a supply step of supplying the powder or granular material stored in the storage section to a fluidized bed dryer;
a fluidized bed drying step of fluidizing and drying the powder or granular material contained in a drying space using a fluidized bed dryer having the drying space;
a discharging step of switching from a closed state in which a path for discharging the powder or granular material from the fluidized bed dryer is closed to a discharging state in which the path for discharging the powder or granular material from the fluidized bed dryer is opened, thereby discharging the powder or granular material;
Including,
A drying method characterized by switching from an exhaust state in which a suction flow generated by a suction fan is applied to the fluidized bed dryer to discharge gas for drying the powder or granular material to a closed state in which a path connecting the suction fan and the fluidized bed dryer is closed to prevent the suction flow from acting on the fluidized bed dryer, and then switching from the storage process to the supply process.