JPH09152273A - Dryer and drying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dryer and a method for drying in which the drying period can be shortened. SOLUTION: The heat pump unit 6 of a heat pump unit chamber 3 regulates the temperature and humidity of the air of a drying chamber 2, and discharges the air to the chamber 2 via a duct chamber 4. A supply fan 15 for generating the counterclockwise circulation flow in the chamber 2 and a supply fan 16 for generating the clockwise circulation flow are provided. Both the fans 15 and 16 are alternately operated at each predetermined time, thereby oppositely directing the circulation air for drying a material to be dried loaded on a drying truck 28 disposed in the chamber 2 at each predetermined time. Far infrared heaters 23, 24 for emitting far infrared rays to the material to be dried loaded on the truck 28 are provided in the chamber 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying apparatus and method, and is effective when used in a drying step in a process of manufacturing dried scallop scallops, for example.

[0002]

2. Description of the Related Art Dried scallop scallops are scallop scallops dried to a water content of 16% or less to withstand long-term storage, and are mainly prized as ingredients for Chinese food.

The manufacturing process of the dried scallop scallop is as shown in the flow chart of FIG. Drying is performed after roasting. Conventionally, the cold air dryer shown in FIG. 9 (a) and the cold air dryer shown in FIG. 9 (b) are used.
After drying to a moisture content of 30 to 40% with a warm air dryer shown in (4), it was dried in the sun to finish the moisture content to 16% or less.

Explaining the cold air dryer shown in FIG. 9 (a), the heat pump device 6 is arranged at one end side inside the dryer, and the drying chamber 2 sucked by the heat pump device 6 is provided.
The air inside is adjusted to an appropriate temperature and humidity, and the adjusted air is discharged into the duct chamber 4, and passes through the duct chamber 4 and is discharged into the drying chamber 2 from the duct outlet 10A. On the other hand, the air flow generated by the blower 31 provided in the upper part of the drying chamber 2 is configured to circulate in the drying chamber 2, and the inside of the drying region 14 in the lower space of the drying chamber 2 It flows horizontally (from the right side to the left side in the figure). Therefore, the drying cart 28 on which the scallops are loaded is arranged in the drying area 14 in the drying chamber 2, and the scallops are loaded on the drying cart 28 by the cold air flowing horizontally in the drying area 14. Are dried. The direction of the cold air is one direction.

Explaining the warm air dryer shown in FIG. 9B, a duct 32 which is connected to the inside of the drying chamber 2 is provided above the drying chamber 2, and the duct 32 has a warm air generator. 33 and a blower 34 are provided, and the warm air generated by the warm air generator 33 is circulated between the duct 32 and the drying chamber 2 by the blower 34. Therefore, the drying truck 28 on which the scallops are loaded is arranged in the drying chamber 2, and the drying truck 2 is driven by the warm air flowing horizontally in the drying chamber 2 (from the right side to the left side in the drawing).
The scallops loaded in No. 8 are dried. The direction of the warm air is one direction.

When the end of the roasting process in the process of manufacturing the dried scallop column shown in FIG. 8 is approached, the water supply from the inside due to internal diffusion cannot catch up with the evaporation from the surface, and the next drying process begins. This tendency is further promoted. When the water content difference between the surface and the inside of the scallop becomes large, the diffusion of water to the surface is further hindered, and it takes a long time to dry. Also, cracking occurs due to excessive drying of the surface.

For this reason, the steps of drying for a short time under relatively mild drying conditions, for a relatively long time of fumigation, and then drying again are repeated. Here, the fumigation refers to a step of reducing the difference in water content between the surface and the inside by waiting for the diffusion of water from the inside while suppressing the surface drying to some extent.

[0008] The sun drying is to reduce the water content of the scallop having a water content of 30 to 40% or less by the radiant heat of the sun and natural ventilation, and at the same time, to give the color and luster peculiar to the dried scallop scallop.

[0009]

As described above, in the conventional cold air dryer or hot air dryer, the number of times of drying to dry the water content to 30 to 40% is large, and the drying period is long. In need. Also, 30-40%
After a long time in the above water condition, white powder and mold are likely to be generated.On the other hand, if the drying conditions are strict to avoid these, the surface will be overly dried and cracks will easily occur. Occurs.

[0010] Since sun drying is difficult to use in bad weather, hot air drying or cold air drying is used as a substitute in such a case, but a desirable color tone and luster cannot be obtained and the quality is deteriorated. Invite.

An object of the present invention is to provide a drying device and a drying method that can shorten the drying period.

[0012]

According to the present invention, the temperature and humidity of the air in the drying chamber are adjusted, the flow of air generated by the fan circulates in the drying chamber, and the circulation flow causes the material to be dried in the drying chamber to move. In a drying device configured to flow through an area in which it is disposed, it is characterized in that the circulation flow can be switched in the opposite direction.

In the above drying device, the flow of the circulating flow is switched to the opposite direction at predetermined time intervals to dry the material to be dried.

In the above drying apparatus, it is desirable to provide a far infrared heater for irradiating the material to be dried with far infrared rays in the drying chamber.

In the conventional drying apparatus shown in FIG. 9 described above, since the air in the drying chamber flows in one direction, the material to be dried which is arranged on the upwind side is arranged on the downwind side. Easier to dry than the material to be dried. Therefore, under the drying condition in which the material to be dried arranged on the leeward side is appropriately dried, the material to be dried arranged on the upwind side is likely to be excessively dried.

On the other hand, in the present invention, the windward side and the leeward side are interchanged, so that a plurality of objects to be dried arranged in the wind flow direction are dried to the same degree. Moreover, when the surface drying progresses on the windward side and the water content difference with the inside becomes large to some extent, the direction of the airflow changes and the airflow rotates downwind, whereby the surface drying is suppressed and the internal diffusion of the water content progresses. Therefore, by appropriately selecting the time for switching the direction of the wind, surface drying does not proceed excessively even after long-term drying, so that one drying time can be lengthened and one As the water content decreases, the water content can be reduced to a predetermined value or less with a small number of times. As a result, the number of man-hours required for drying can be reduced, and the period in which the material to be dried is likely to deteriorate is shortened, so that generation of white powder or mold is prevented. Further, since the surface drying does not proceed excessively, it is possible to prevent the occurrence of cracks.

When it is impossible to dry in the sun due to bad weather, the far-infrared heater irradiates the material to be dried with far-infrared rays, whereby browning can be appropriately suppressed and the color tone and gloss can be adjusted.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 show an embodiment of the present invention. The drying device used in the drying process in the manufacturing process of the dried scallop scallop includes a drying chamber 2, a heat pump device chamber 3, and a duct chamber 4 in the device body 1.

The apparatus main body 1 is a horizontally long rectangular box as viewed from the front, and has left and right side walls 1a and 1b, front and rear side walls 1c, and
1d and the upper wall 1e. In the apparatus main body 1, a vertical partition wall 5a is provided near the left end and extends to the upper and lower side walls 1c and 1d, and a vertical partition wall 5a is provided across the front and rear side walls 1c and 1d from the upper end to the right end side of the partition wall 5a. Horizontal bulkhead 5 extending to the central position
b, a vertical partition wall 5c extending over the front and rear side walls 1c, 1d and extending from the tip of the horizontal partition wall 5b to the upper wall 1e, and provided on the left end side over the front and rear side walls 1c, 1d. It is provided with a horizontal partition wall 5d formed between an upper position of the vertical partition wall 5a and the left side wall 1a of the apparatus body 1.

The drying chamber 2 is formed by the right side wall 1b and the upper wall 1e of the apparatus main body 1, two vertical partition walls 5a and 5c and a horizontal partition wall 5b arranged between them. The heat pump device room 3 has a vertical partition wall 5 on the left end side.
a, a left side wall 1a of the apparatus main body 1, and a horizontal partition wall 5d arranged between them. Duct room 4
Is formed by the left side wall 1a and the upper wall 1e of the apparatus main body 1, and four partition walls 5a to 5d.

A plurality of heat pump devices 6 are arranged in the heat pump device chamber 3, and the heat pump device 6 has a suction port 7 on the side facing the vertical partition wall 5a.
The discharge port 8 provided at the upper end is arranged in the opening formed in the horizontal partition wall 5d. A plurality of suction ports 9 are opened at intervals in the front-rear direction at the lower end of the vertical partition wall 5a facing the suction port 7 of the heat pump device 6. The heat pump device 6 has dehumidifying, cooling, and heating functions, and the air in the drying chamber 2 sucked from the suction port 9 through the suction port 7 by the heat pump device 6 has a predetermined temperature and humidity within the heat pump device 6. After being discharged, it is discharged from the discharge port 8 into the duct chamber 4. 6a is a heat pump outdoor unit.

The air that has entered the duct chamber 4 flows through the duct chamber 4 and is discharged into the drying chamber 2 from a plurality of duct outlets 10 which are opened in the upper horizontal partition wall 5b at intervals in the front-rear direction. It

In the drying chamber 2, the side walls 1 at the front and rear of the apparatus main body 1 are provided.
A horizontal partition wall 11 is provided over c and 1d.
The partition wall 11 is located below the horizontal partition wall 5b in which the duct outlet 10 is formed, has a gap 12 at the right end with the right side wall 1b of the apparatus body 1, and has a vertical partition wall at the left end. There is a gap 13 between the gap 5a and 5a. Therefore, the space above the horizontal partition 11 and the space below it are communicated with each other through the left and right gaps 12 and 13, and a circulation path is formed between them, and the horizontal partition 11 is formed by the blower fan described later. The air in the drying chamber 2 circulates through the space above and below. The space below the horizontal partition wall 11 is a space in which the trolley for drying 28 on which the material to be dried is placed is arranged, and constitutes a drying region 14 of the material to be dried.

In the drying chamber 2, a plurality of fans 15 and 16 for blowing air in mutually opposite directions are alternately arranged on the horizontal partition wall 11 in the front-rear direction. That is, a plurality of blower fans 15 (hereinafter referred to as counterclockwise blower fans 15) that generate a counterclockwise circulation flow are arranged at intervals in the front-rear direction, and a clockwise circulation flow is provided between them. An air blower fan 16 (hereinafter, referred to as a clockwise air blower fan 16) that causes the air flow is arranged. And
Shutters 17 and 18 that can be opened and closed are arranged on the back side of the blower fans 15 and 16. The horizontal partition wall 5b in which the duct outlet 10 is formed is arranged at a position higher than the blower fans 15 and 16.

Blower fans 15 and 16 and shutters 17 and 1
The operation of No. 8 will be described. When the left-handed blower fan 15 is operating, the right-handed blower fan 16 is arranged so that the wind does not enter the suction side through the right-handed blower fan 16.
The shutter 18 on the back side of the fan is closed, and when the clockwise blower fan 16 is operating, the wind blows counterclockwise.
The shutter 17 on the back side of the counterclockwise blower fan 15 is closed so as not to go around to the suction side through. It should be noted that the intake ports of the blower fans 15 and 16 and the upper wall 1 of the apparatus body 1 are
The partition wall 1 is formed over the front and rear side walls 1c and 1d between
9 and 20 are provided respectively.

Therefore, the air flow generated by the counterclockwise blower fan 15 enters the drying area 14 from the space above the horizontal partition wall 11 through the left gap 12 and returns to the upper space from the right gap 13. Create a flow. At this time, the shutter 17 on the back side of the counterclockwise blower fan 15 is open, and the shutter 18 on the backside of the clockwise blower fan 16 is closed. When the counterclockwise blower fan 15 operates for a predetermined time, the counterclockwise blower fan 15 stops operating, and then the clockwise blower fan 16 operates for a predetermined time. The airflow generated by the clockwise blower fan 16 enters the drying area 14 from the space above the horizontal partition wall 11 through the right-side gap 13, and then returns to the upper space from the left-hand gap 12 to generate a circulating flow. At this time, the shutter 18 on the back side of the clockwise blower fan 16 is open, and the shutter 17 on the back side of the counterclockwise blower fan 15 is closed. In this way, the left-hand blower fan 15 and the right-hand blower fan 16 are alternately operated for a predetermined time, so that the circulating flow moves horizontally in the drying region 14 (left-right direction in the drawing).
The flow direction of the circulating flow is opposite to that of the circulating flow every predetermined time.

A plurality of hot air heaters 21 are arranged on one end side of the horizontal partition wall 11 of the drying chamber 2, and a plurality of humidifiers 22 are arranged on the other end side. Also, the drying room 2
The far-infrared heaters 23 and 2 are respectively provided on the right side wall 1b of the apparatus main body 1 facing the drying area 14 and the vertical partition wall 5a.
A plurality of 4 are fixed. A far-infrared heater may be installed in the drying chamber 2 by using a stand type heater.

The operation of the drying device will be described below. As shown in FIG. 4, the drying container 25 is a rectangular box having an open top, and a large number of ventilation holes 26 are formed on each surface. The drying container 25, on which a large number of scallop posts 27, which are the objects to be dried, are placed, is placed on a drying carriage 28. The drying carriage 28 is a rectangular box-shaped carriage constituted by a frame, and a large number of horizontal mounting plates 29 are fixed vertically.
Therefore, a truck for drying 28, in which a drying container 25 accommodating a large number of scallops 27, which is an object to be dried, is placed on each mounting plate 29, is a doorway formed on the front side wall 1c of the apparatus body 1 of the drying apparatus. The door 30 is disposed in the drying area 14 of the drying chamber 2. A plurality of drying carts 28 are arranged side by side in the drying area 14 of the drying chamber 2 in the front, rear, left and right directions.

The temperature and humidity of the air in the drying chamber 2 are adjusted to appropriate temperatures and humidity by the heat pump device 6. That is, the air in the drying chamber 2 sucked from the suction port 9 through the suction port 7 by the heat pump device 6 is discharged to the duct chamber 4 through the discharge port 8 after being heated to a predetermined temperature and humidity in the heat pump device 6. , The air that entered the duct chamber 4
It flows through the duct chamber 4, and is discharged into the drying chamber 2 from a plurality of duct outlets 10 that are opened in the horizontal partition wall 5b. In this way, the temperature and humidity of the air in the drying chamber 2 are adjusted to the appropriate temperature and humidity. Further, the hot air heater 21 and the humidifier 22 are appropriately operated to adjust the temperature and humidity of the air in the drying chamber 2.

As for the blower fans 15 and 16, the clockwise blower fan 16 is in a stopped state, and the counterclockwise blower fan 1 is
5 is activated. The airflow generated by the counterclockwise blower fan 15 enters the drying area 14 from the space above the horizontal partition wall 11 through the left gap 12 and returns from the right gap 13 to the upper space. At this time, the scallop column 27, which is the object to be dried, loaded on each of the drying carriages 28 is dried by the circulation flow that flows horizontally (from the left side to the right side in the drawing) in the drying area 14.

Then, the scallop column 27 is dried for a predetermined time, and a trolley 28 for drying located on the windward side and located near the left end.
When the surface of the scallops 27 loaded on the table has dried and the water content inside the scallops 27 has increased to some extent, the operation of the counterclockwise blower fan 15 is stopped and the clockwise blower fan 16 is stopped.
Operates. The air flow generated by the clockwise blower fan 16 moves from the space above the horizontal partition wall 11 to the gap 1 on the right side.
A circulation flow is generated through 3 into the drying area 14 and returns from the left clearance 12 to the upper space. As a result, the direction of the circulation flow passing through the drying area 14 of the drying chamber 2 is switched to the opposite direction, and the trolley 28 for drying near the left end, which was on the windward side when the counterclockwise blower fan 15 was operating, moves to the leeward side. As a result, the surface drying of the scallops 27 loaded on the drying cart 28 near the left end is suppressed, and the internal diffusion of water is promoted.

When the internal diffusion of water has progressed to a certain extent, the operation of the clockwise blower fan 16 is stopped and the counterclockwise blower fan 15 is actuated, so that the scallop column loaded on the drying cart 28 near the left end. Surface drying of 27 proceeds. Then, when the water content difference with the inside becomes large to some extent, the operation of the counterclockwise blower fan 15 is stopped, and the clockwise blower fan 16 is operated. Below, both blower fans 1
The operations 5 and 16 are alternately repeated a predetermined number of times.

In the above, the trolley 2 for drying near the left end is used.
Although the dried state of the scallop scallops 27 loaded in No. 8 has been described, the scallop scallops 27 loaded on the drying cart 28 near the right end are also dried in the same manner as above.

As described above, in the drying device according to the present embodiment, the windward side and the leeward side are exchanged with each other, so that the scallop column 27 loaded on each of the drying carts 28 is dried to the same degree. In addition, the surface drying progresses on the windward side, and when the water content difference between the inside and the inside becomes large to some extent, the direction of the wind changes and the surface windward is changed to suppress the surface drying,
Since the internal diffusion of moisture progresses, even if it is dried for a long time, surface drying does not proceed excessively, and one drying time can be lengthened. It can be below a predetermined percentage. As a result, the number of man-hours required for drying can be reduced, and the period during which the scallops are likely to deteriorate is shortened, so that generation of white powder or mold can be prevented. Further, since the surface drying does not proceed excessively, it is possible to prevent the occurrence of cracks.

As described above, the far infrared ray heaters 23 and 24 are operated at a stage when the water content is reduced to a predetermined value or less, and the far infrared rays are applied to the scallop column 27 which is an object to be dried and is loaded on each of the drying carts 28. By the irradiation, browning is appropriately suppressed, and the color tone and gloss are adjusted.

It is necessary to change the drying conditions for drying the scallop scallops according to the dry state. The scallop scallop drying device is configured so that the drying condition can be selected according to the dry state of the scallop. That is, the temperature of the drying chamber 2, the set values of humidity, dehumidification and cooling of the heat pump device 6,
Several kinds of operation patterns in which the switching of the heating operation, the use of the hot air heater 21, the humidifier 22, and the far infrared heaters 23 and 24 are set in advance are prepared and can be selected.

5 and 6 show a scallop scallop drying process by the drying device and a scallop scallop drying process by the conventional drying device in the present embodiment, respectively. FIG.
FIG. 5A shows the process time and the number of days elapsed in the drying process by the drying device (Example 1) that uses the circulation flow switching and the far infrared heater in combination, and FIG. 5B shows only the circulation flow switching the far infrared ray. The process time and the elapsed days of a drying process by a drying device (Example 2) which does not use a heater are shown.
Further, FIG. 6A shows the process time and the number of days elapsed in the drying process by the conventional drying device (Comparative Example 1) having no circulating flow switching function, and FIG. The process time and elapsed days of a drying process by a drying device (Comparative Example 2) provided with a heater are shown. FIG.
The far-infrared heater was used every time during the drying process in the drying steps of (a) and FIG. 6 (b). In addition, FIG. 7 shows a state of reduction of water with respect to the number of days elapsed for drying by the two types of drying devices of Example 1 and Comparative Example 1.

Comparing Example 1 with Comparative Example 1, in Example 1, the number of times of drying is reduced by 3 times and is halved because the water content is reduced by one drying. In addition, since it is dried uniformly and there is little difference in water content between the surface and the interior, the fumigation time is shortened,
The drying period has been shortened by 15 days. As a result, the required man-hours are significantly reduced. In Example 2, the first half of the drying was the same as that of Example 1, but a difference was observed in the latter half, and as a result, the number of times of drying was reduced by 2 times and the drying period was shortened by 10 days as compared with Comparative Example 1. Has been done.

The quality of the dried scallop scallops by the conventional drying device is compared with the quality of the dried scallop scallops by the drying device in the present embodiment. Table 1 shows the results of inspection according to the criteria shown in Table 2, Table 3, and Table 4. Tables 2 and 3 show the categories of dried scallop scallops according to the dried scallop scallop rating standard (Hokkaido Gyoren voluntary rating inspection standard), and Table 4 is the same for dried scallop scallop (crushed). Indicates the product category.

In the case of using the drying apparatus of Example 1, cracking,
As a result of a decrease in white powder and an improvement in color tone and gloss, the proportion of 1st grade products increased by 20% and the proportion of crushed products was 9% less than in Comparative Example 1. Moreover, the ratio of the first grade product is increased by 6% and the ratio of the crushed product is reduced by 4% as compared with Comparative Example 2. In the case of using the drying apparatus of Example 2, the performance in the first half of drying is the same as that of Example 1, but in the latter half of adjusting the color tone / gloss, the effect of not irradiating far infrared rays appears, and a part of the color is thin and glossy. There are few things. As a result, the proportion of the first-class products is reduced by 9% as compared with Example 1, but the proportion of the first-class products is increased by 11% and the proportion of the crushed products is 8% as compared with Comparative Example 1.
Few. Compared to Comparative Example 2 which uses a far infrared heater, the ratio of crushed products is reduced by 3%.

[0041]

[0042]

[0043]

Stone ball: A scallop that is remarkably hard because it has been boiled in turbid water for boiling because it contains a large amount of salt or insufficiently exchanged water. Old shellfish: A scallop that has a very tight meat fiber due to the slow growth of shellfish, and is extremely hard, and has a steep horn angle. Ame jade: A scallop with poor meat tightness due to a slight deterioration of the center of the scallop due to insufficient ripening or poor drying process. Hanasakikai: A dried scallop that is dried due to excessive ripening and has many cracks on the surface of the scallop that looks like pomegranate.

[0045]

[0046]

As described above, according to the present invention, the air whose temperature and humidity are adjusted is circulated alternately in opposite directions in the drying chamber, so that any position in the drying area in the drying chamber is circulated. Since the drying progresses with a small difference in water content between the surface and the inside, it is possible to extend the drying time once, and as a result, the number of times of drying is reduced and the drying period is also shortened, so the number of steps is reduced. To do. In addition, white powder and mold defects can be reduced by reducing cracking defects due to excessive surface drying and shortening the period of high water content. In addition, the far infrared heater provided in the drying chamber irradiates the object to be dried with far infrared rays at a suitable time, thereby causing a poor color tone or gloss due to insufficient drying in the sun due to bad weather, or Good color tone and gloss can be achieved without causing browning failure due to excessive sun drying.

[Brief description of the drawings]

1A and 1B show an embodiment of the present invention, in which FIG. 1A is a sectional view taken along the line AA of FIG. 2A, and FIG.
2B is a sectional view taken along the line B, and FIG. 2C is a sectional view taken along the line CC of FIG.

FIG. 2 shows an embodiment of the present invention, in which (a) is a plan view and (b) is a front view.

FIG. 3 is an explanatory diagram showing a flow of air in the drying device according to the embodiment of the present invention.

FIG. 4 is a partial cross-sectional front view showing a truck for drying on which a scallop column is loaded.

FIG. 5 is a flowchart showing the process time and the number of elapsed days of the drying process, (a) showing Example 1 and (b) showing Example 2.

FIG. 6 is a flowchart showing the process time and the number of days elapsed in the drying process, where (a) shows Comparative Example 1 and (b) shows Comparative Example 2.

FIG. 7 is a diagram showing the relationship between the number of days elapsed after drying and the water content ratio.

FIG. 8 is a flowchart showing a manufacturing process of dried scallop scallops.

FIG. 9A is a front sectional view showing a cold air dryer, and FIG.
FIG. 3 is a front sectional view showing a warm air dryer.

[Explanation of symbols]

 1 Device body 1a, 1b, 1c, 1d Side wall 1e Upper wall 2 Drying chamber 3 Heat pump device chamber 4 Duct chamber 5a, 5b, 5c, 5d Partition wall 6 Heat pump device 6a Heat pump outdoor unit 7 Suction port 8 Discharge port 9 Suction port 10 Duct Outlet 11 Partition 12,13 Gap 14 Drying area 15,16 Blower fan 17,18 Shutter 19,20 Partition 21 Hot air heater 22 Humidifier 23,24 Far infrared heater 25 Drying container 26 Vent hole 27 Scallops 28 Drying cart 29 Mounting plate 30 doorway

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yuichi Kobayashi, 461-6 Satozuka, Toyohira-ku, Sapporo, Hokkaido Hokkaido Electric Power Co., Inc. Research Institute (72) Mitsuaki Ishioka, 461-6, Satozuka, Toyohira-ku, Sapporo, Hokkaido Company Research Institute

Claims (4)

[Claims] 1. The temperature and humidity of the air in the drying chamber are adjusted, the flow of air generated by a fan circulates in the drying chamber, and the circulating flow flows in the region where the material to be dried is arranged in the drying chamber. In the drying device configured as described above, the drying device is configured such that the flow of the circulation flow can be switched in the opposite direction. 2. The drying apparatus according to claim 1, wherein a far-infrared heater that irradiates the material to be dried with far-infrared rays is provided in the drying chamber. 3. The temperature and humidity of the air in the drying chamber are adjusted, the air flow generated by the fan circulates in the drying chamber, and the circulating flow flows through the area in the drying chamber where the material to be dried is arranged. Thus, in the drying method for drying the material to be dried, the flow of the circulating flow is switched to the opposite direction at predetermined time intervals. 4. The drying method according to claim 3, wherein the material to be dried in the drying chamber is irradiated with far infrared rays.