JPH04207120A - Storage device - Google Patents

Abstract

PURPOSE:To supply a nitrogen gas having a set oxygen concentration to storage houses by installing a concentration controlling means of regulating reflux of a nitrogen gas separated and formed in adsorption tanks from a pressure accumulation tank to the adsorption tanks and an adsorption time in the adsorption tanks. CONSTITUTION:When a gas concentration in storage houses 2A to 2C is set at low oxygen concentration, a controller 6 refluxes a nitrogen gas in a pressure accumulation tank 33 to adsorption tanks 21 and 22 and when in high oxygen concentration, a half cycle time of the adsorption tanks 21 and 22 is shortened and a time from supply of a raw material gas to the adsorption tanks to taking out of a nitrogen gas separated and formed with an adsorbent is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a storage device, and more particularly to a storage device in which a storage chamber is filled with a gas to maintain the freshness of stored items.

2. Description of the Related Art Fresh foods such as vegetables and fruits are generally stored in storage devices to maintain their freshness until they are shipped.

In addition, for long-term preservation of these stored items, the inside of the storage is inactivated by keeping the temperature low enough to prevent the stored items from freezing, the oxygen concentration inside the storage is lowered to the minimum necessary, and carbon dioxide is added to have a respiration effect. It is considered to be the best way to suppress this, and research on this type of research is currently being continued. A storage method that takes advantage of this reduction is called a CA (controlled atmosphere or chondral atmosphere) storage method.

In a storage device using this method, the inside of the storage chamber is maintained at the minimum necessary oxygen (O2) level, and the necessary maximum amount of carbon dioxide gas (CO, gas) is put in, and the rest is filled with non-containing substances such as nitrogen gas (N2 gas). Is it necessary to supplement with active gas?

In this manner, in the storage device, first, N2 gas or C02 gas is injected into the storage to reduce the 02 gas concentration in the storage, or PSA (Pre
It has been considered to supply N2 gas into the refrigerator using a nitrogen gas generator (Sure Swing Adsorption).

Furthermore, since the optimal ratio of O2 gas, CO2 gas, and N2 gas in the storage is determined for each type of fruit or vegetable, it is necessary to always maintain a constant ratio depending on each fruit or vegetable. However, as mentioned above, since the stored material breathes, the 02 gas is consumed over time and CO2 gas is generated.
The gas concentration ratio inside the refrigerator changes. Therefore, during the storage period, it is necessary to monitor changes in the gas concentration inside the refrigerator and adjust it so that it always remains constant.

Problems to be Solved by the Invention However, when adjusting the gas concentration ratio in the storage using the above-mentioned PSA type nitrogen gas generator, the separated and generated N2 gas is supplied into the storage using an adsorption tank. When adjusting the concentration ratio to suit the fruits and vegetables stored in the refrigerator,
Another problem is that it takes a considerable amount of time to obtain gas with a desired oxygen concentration by changing the operating conditions of the nitrogen gas generator. Therefore, there is a problem that a single nitrogen gas generator cannot supply gases of different concentrations to each of a plurality of storage units storing different types of fruits and vegetables.

Therefore, an object of the present invention is to provide a storage device that solves the above problems.

Means for Solving the Problems The present invention provides a storage chamber in which stored materials are stored, an adsorption tank filled with an adsorbent inside, and a pressure-accumulated nitrogen gas separated and produced by the adsorbent in the adsorption tank. A storage device comprising a tank and supplying gas from the tank to the storage such that the gas concentration ratio in the storage is a preset concentration, the gas concentration in the storage is set to a low oxygen concentration. When the nitrogen gas in the tank is refluxed into the adsorption tank, and when the gas concentration in the storage is set to a high oxygen concentration, the raw material gas is supplied to the adsorption tank and then separated and produced by the adsorbent. The apparatus is equipped with a concentration control means for shortening the time required to take out the nitrogen gas.

Effect: According to the preset gas concentration ratio, when the oxygen concentration is low, the nitrogen gas in the tank is returned to the adsorption tank, and when the oxygen concentration is high, the time from supplying the raw material gas to the adsorption tank to taking out the nitrogen gas. By shortening the time, nitrogen gas having a set oxygen concentration can be generated in a shorter time and can be stably supplied into the storage.

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a configuration diagram of storage bag #1, which is an embodiment of the present invention. Roughly speaking, storage device 1 is storage 2 (28 to 2C),
Modified air generation unit 3゜Air supply unit 4. The gas concentration detection unit 5 is composed of a programmable controller (hereinafter simply referred to as controller) 6.

The storages 2A to 2C each store different types of fruits and vegetables therein, and are configured so that the insides thereof are maintained at a low temperature to the extent that the stored items do not freeze by a refrigeration device (not shown).

In this embodiment, apples are stored in the first two storage rooms, shiitake mushrooms are stored in the second storage room 2B, and broccoli mushrooms are stored in the third storage room 2C. Furthermore, the storage chambers 2A to 2C are configured to be airtight when the door for loading and unloading stored items is closed, and a fan (not shown) is also provided inside the chamber to agitate the inside air. It is as follows.Each storage 2A to 2C
Inside, there are 02 sensors 7A to 7C, Co□ sensor 8A.
~8C is provided.

9 is a modified air supply pipe (hereinafter referred to as modified air piping) connected to the modified air generation unit 3, lO is an oxygen supply pipe connected to the air supply unit 4 (hereinafter referred to as 02 pipe), and lIA to 11C are Storage 2A each with discharge piping
2C, and exhaust valves 53A to 53C are provided in each of the exhaust arrangements 11A to 11. The modified air pipe 9 has a throttle valve 12. A three-way solenoid valve I3 is provided. The modified air from the modified air generation unit 3 is throttled to a predetermined flow rate by the throttle valve 12, and is supplied to the humidifier I9 when the three-way solenoid valve 13 is excited. Furthermore, the modified air from the humidifier 19 is supplied to each storage 2A to 2c via a pipe 2o and on-off valves 20A to 20C. In addition, an air supply valve 14 and a throttle valve 15 are arranged in the 02 pipe 1o, and air from the air supply unit 4 is supplied to the humidifier 51 via the throttle valve 15 when the air supply valve I4 is opened. Supplied.

Furthermore, the air from the humidifier 51 is transferred to the piping 52 and the on-off valve 5.
It is supplied to each storage 2A-2c via 2A-52C.

The modified air generation unit 3 is a gas separation device that is supplied with air, which is mainly a mixed gas of nitrogen and oxygen, as a raw material gas and separates and generates nitrogen and oxygen, which are modified air. This modified air generation unit 3 is connected to an air supply unit 4 via a pipe 16.

The air supply unit 4 includes a compressor 17 and a dryer 18 that dries the compressed air from the compressor 17. The dryer 18 is connected to the pipe 16.10, and the air from the dryer 18 is supplied to the storages 2A to 2C and the modified air generation unit h3.

Here, the configuration of the modified air generation unit 3 will be explained.

In Figure 1, 21+22 is the 1st. The adsorption tanks 21 and 22 of the second adsorption tank are each filled with adsorbents 21A and 22A (shown with a satin finish in the figure) made of molecular sieve carbon that adsorbs oxygen.

23 and 24 are pipes for discharging gas from the adsorption tank 2m22 during desorption, and are connected to the common discharge pipe 25, respectively.
The discharge pipe 25 is designed to discharge adsorbed dregs (in this embodiment, adsorbed oxygen). Gas discharge valves 26 and 27 are provided in the middle of the pipes 23 and 24, respectively, which are electromagnetic valves that alternately discharge the desorbed gas in the adsorption tanks 21 and 22 every half cycle.

On the other hand, 28.29 is a pipe that communicates between the adsorption tanks 21.22, 30 is an extraction pipe connected to each of the pipes 28.29, and a predetermined short period of time is provided in the middle of each pipe 28.29 at the end of a half cycle. Pressure equalization valves 31 and 32 are provided, respectively, which open to equalize the pressure between the adsorption tanks 2L22. In addition, the extraction pipe 3o is connected to the generated modified air (N containing low concentration 0.0 gas).
A buffer tank 33 for storing 2 dregs) and a take-out valve 43 are disposed in the middle thereof.

Further, a pressure reducing valve 38 is disposed in the pipe 16, and an air supply valve 41.42 is disposed in a pipe 39.40 communicating with the pipe 16 and connected to the adsorption tank 21.22.

36 is a pipe communicating between pipes 28 and 29, 37a and 37
Reference numeral b indicates a check valve provided in the middle of the pipe 36, and is arranged so as to recirculate the modified air from the buffer tank 33, respectively.

Reference numeral 53 denotes a communication pipe that communicates between the pipes 9 and 36, and a reflux valve 54 and a throttle valve 55 are disposed in the middle of the pipe.

A modified air pipe 9 is connected to the buffer tank 33 for supplying the modified air generated by the modified air generating unit 3 to the storages 2A to 2c, and the throttle valve 12. In addition to the three-way solenoid valve 13, a take-out valve 44 consisting of a solenoid valve and a buffer tank 33 detect 02a degrees contained in the modified air. Two sensors 45a are provided. This O2 sensor 45a. 2a degree total 45
The 02a degree meter 45 is connected to. 2 sensors 45a
The concentration is detected by the detection signal from.

The gas concentration detection unit 5 includes 02a degree meters 46A to 46C,
Co211 degree meter 47A ~ 47Ct - 6° each 0□ concentration meter 46A ~ 46C, C○2 concentration meter 47A ~ 47C are connected to the above 02 sensor 7A ~ 7c, CO2 (? Based on detection signals from sensors 78 to 7C and 8A to 8c, it is output whether the concentration is within the set range or not.

The signal output from the gas concentration detection unit 5 is input to the controller 6. The controller 6 includes a modified air generation unit 3 based on detection signals from each sensor. While operating the air supply unit 4, the three-way solenoid valve 13. Air supply valve 14 and reflux valve 54. 02 concentration in the storage chambers 2A to 2C by changing the half cycle time of the adsorption tanks 21 and 22.

A program is input to control the opening and closing of each electromagnetic valve so that the C02 concentration reaches a predetermined value.

Reference numeral 48 indicates a switch hook, the start switch 48a of the storage device 1, and the 0□ concentration in the storage 2.

02 concentration setting switch 48b, C to set C○2 concentration
An O□ concentration setting switch 48c is provided and connected to the controller 6. Moreover, in the switch box 48,
Modified air supply switch 49a, modified air generation switch 49b for apples, modified air generation switch 49c for shiitake mushrooms
, a broccoli modified air generation switch 49d, an apple air supply switch 49e, a shiitake mushroom air supply switch 49f, and a broccoli air supply switch 49g.

Here, the PSA used in the storage device 1 having the above configuration is
The basic operation of the modified air supply unit 3 will be explained.

When the start switch 48a of the switch box 48 is operated, the compressor 1 is started, and the air compressed by the compressor 17 (after being dehumidified through the dryer 18, passes through the piping 6 and is brought to a predetermined pressure by the pressure reducing valve 38). The pressure is reduced.Then, the modified air generation unit 3 performs the following steps in sequence to generate modified air (N2
gas) is produced.

■ "The pressure is reduced in the first adsorption tank 21, and the pressure is increased in the second adsorption tank 22" In other words, the air supply valve 42 and the gas discharge valve 26 are opened, and compressed air is supplied into the adsorption tank 22 and adsorbed. The remaining gas in the tank 21 is discharged through the discharge pipe 25.

Therefore, in the adsorption tank 22, oxygen from the compressed air or the adsorbent 22
A is adsorbed and high purity nitrogen gas is produced. and,
The pressure equalization valve 32 and the extraction valve 43 are opened, and the adsorption tank 22
The modified air separated and generated is supplied to the buffer tank 33. During this time, in the adsorption tank 21, the oxygen adsorbed by the adsorbent 21Aζ is desorbed and discharged into the atmosphere.

■ Pressure equalization between the U adsorption tanks 21 and 22 J The gas supply valve 42. which was opened in (■) above. The discharge valve 26 and the take-out valve 43 are closed, and the other pressure equalization valve 31 is opened. As a result, the pressurized modified air in the adsorption tank 22 is supplied to the depressurized adsorption tank 21 through the pressure equalization valves 32 and 31, and the yield in the adsorption tank 21 is increased.

■ "The first adsorption tank 21 is pressurized and the second adsorption tank is depressurized. After closing the pressure equalization valves 31 and 32 that were opened in the above step (■),
The air supply valve 41 and the gas discharge valve 27 are opened.

Therefore, the compressed air that has passed through the dryer 18 is supplied to the adsorption tank 21, and the residual gas in the adsorption tank 22 is discharged. Therefore, in the adsorption tank 21, oxygen in the compressed air is adsorbed by the adsorbent 21A, and highly pure nitrogen gas is generated. Then, the pressure equalization valve 31 and the take-out valve 43 are opened, and the modified air generated in the adsorption tank 21 is supplied to the buffer tank 33. During this time, in the adsorption tank 22, the oxygen adsorbed by the adsorbent 22A is desorbed and discharged into the atmosphere.

■ "Pressure equalization between adsorption tanks 21 and 22" Gas supply valve 41 opened in step (■) above. The discharge valve 27 and the take-out valve 43 are closed, and the other pressure equalization valve 32 is opened. As a result, the pressurized modified air in the adsorption tank 21 passes through the pressure equalization valves 31 and 32, and the pressure in the adsorption tank 21 is reduced.
The yield in the adsorption tank 22 is increased.

For modified air generation unit 3, perform steps 1 to 1 above.
The cycle is repeated to accumulate modified air in the buffer tank 33. Note that the take-out valve 44 of the modified air generating unit 3 during operation is always open.

Figure 2 shows the modified air in the buffer tank 33 being transferred to the adsorption tank 2.
．． Figure 2 shows the experimental results comparing the change in oxygen concentration when refluxing to 22 and the change in oxygen concentration when there is no reflux. You can see what you can get.

Figure 3 shows the change in oxygen concentration when the half cycle time (steps ■, ■ or ■, ■) of the modified air generation unit 3 is shortened to 4 seconds, and when the time is shortened to 4 seconds or more. These are the experimental results. From Figure 3, it can be seen that when the half cycle is shortened to 4 seconds, modified air with a high oxygen concentration can be obtained in a shorter time.

Next, the operation of the storage device 1 by each switch operation of the switch box 48 will be explained.

In this example, the temperature in each of the storage rooms 2A to 2C is lowered, and each fruit and vegetable is stored using the CA storage method, and the storage conditions for apples are 3≦0□≦5%, 4≦CO2
≦6%, and the storage conditions for shiitake mushrooms are 1.5≦02≦2.5
%, 9≦002≦11%, broccoli storage conditions are 2≦
02≦4%.

3≦CO2≦5% and 02 concentration setting switch 48b, respectively;
It is set by operating the C○2 concentration setting switch 48c.

A modified air supply switch 49a of the switch box 48 switches the three-way solenoid valve 13 to supply modified air from the throttle valve 12 to the humidifier 19. In addition, the apple modified air generation switch 49b sets the half cycle time of the modified air generation unit 3 to the time required to obtain the upper limit of oxygen concentration necessary for preserving apples, and operates the modified air generation unit 3. To supply modified air to storage 2A, on-off valve 2OA
and opens the exhaust valve 53A.

Furthermore, in this embodiment, in order to obtain modified air with a preset oxygen concentration in a short time, a reflux operation or a shortening operation to half a cycle is performed for a predetermined period of time. In the reflux operation, by opening the reflux valve 54, the modified air in the buffer tank 33 can be supplied to the adsorption tank 21.22 via the pipe 53.36. At that time, the check valves 37a and 37b are set so that the modified air flows into the adsorption tank under pressure reduction among the adsorption tanks 21 and 22.
Or open the valve. Moreover, when the half cycle time is shortened to 4 seconds, the above-mentioned reflux operation is also used.

Because fruits and vegetables breathe, they consume 02 and C
Releases O□. Therefore, the atmosphere inside the refrigerator decreases in 0□ and increases in CO2. Therefore, the concentration of 0□ in the refrigerator, C○
In order to keep the 02 concentration within the range suitable for each fruit or vegetable, air is supplied into the refrigerator to raise the 02 concentration to the upper limit, and then modified air controlled to the upper limit of the 02 concentration is supplied into the refrigerator. The CO2 concentration is lowered by removing CO2 without changing the 02 concentration. By performing such a concentration control operation, the controller 6 controls the 0□ concentration in the refrigerator to the upper limit value and the CO2 concentration to the lower limit value.

More specifically, the controller 6 executes the process shown in FIG. 4.

Now, the gas concentration ratio in storage 2A for apples is 02, which is the lower limit of 3% or CO2 or the upper limit of 6% due to the respiration effect of apples.
When the apple air supply switch 49 is reached, the operator
Turn on e. This allows the air supply valve 14. The on-off valve 20A and the exhaust valve 53A are opened, and compressed air from the compressor 17 is supplied to the two storage units. Therefore, when the 02 concentration in the refrigerator increases and reaches the upper limit of 5%, the switch 49e is turned off.

Next, when the apple modified air generation switch 49b is turned on in step Sl (hereinafter the step will be omitted), the controller 6 starts the compressor 17 and the dryer 18.

In S2, it is checked whether the 0□ concentration of the modified air is to be increased. If the 0□ concentration is not to be increased, the process moves to S4, and the modified air in the buffer tank 33 is transferred to the adsorption tank 21.2.
Reflux to 2.

Then, in the next step 85, the operations of steps (1) to (2) are repeated based on preset conditions. When producing modified air for apples, half cycle 11 is used to obtain a 02 concentration of 5%.
Drive in seconds. During pressurization, the modified air from the buffer tank 33 is returned to the adsorption tanks 21.22.
22 gas replacement rate has been increased.

Immediately after starting operation, corrected air at the set concentration cannot be obtained, so
After performing the reflux operation for a certain period of time, when the concentration value of the 02 concentration meter 45 reaches 5% (S6), when the modified air supply switch 49e is turned on, the three-way solenoid valve 13 is switched (37
), the modified air in the buffer tank 33 is supplied to the storage 2A. Continue supplying modified air until the CO2 concentration in the storage 2A reaches the lower limit of 4% (S8), and when the CO2 concentration in the refrigerator reaches the lower limit of 4%, the modified air supply switch 49a and the apple modified air generation switch 49b are turned off. When the compressor 17. The dryer 18 and modified air generation unit 3 are stopped (S9).

If the 02 concentration of the modified air is to be increased in S2, the process moves to S3, where the half cycle time of steps (1) to (2) of the modified air generation unit 3 is shortened to 4 seconds to generate modified air with a high 02 concentration.

In addition, when the 02 concentration reaches the lower limit or the CO2 concentration reaches the upper limit in the other storages 2B and 2C, air is supplied into the storage in the same way as in the apple storage 2A, and the modified air generation unit 3 is operated to maintain the predetermined level. The corrected concentration air is supplied to the storage chambers 2B and 2C.

For example, the gas concentration in apple storage 2A is 02 = 5%,
Shiitake storage 2B when adjusted to C02 = 4%
02 concentration or lower limit 1.5% or C02 concentration or upper limit 11
%, the operator turns the shiitake mushroom correction air generation switch 49c and the shiitake mushroom air supply switch 49f.
operate.

As a result, air is supplied to the storage chamber 2B to raise the upper limit of the ○2 concentration in the chamber to 2.5%, and the modified air generation unit 3 changes the concentration of 02 for shiitake mushrooms from 5% for apples, which had been generated up until then. 02 concentration: Change the concentration to 5945 modified air.

At that time, the half cycle time of the modified air generation unit 3 is changed from 11 seconds to 22 seconds. This produces modified air with a low 02 concentration.

Furthermore, a reflux operation is performed to shorten the time it takes for the 02 concentration of the modified air to change from 5% to 2.5%.

Note that the time for the reflux operation is preset in the controller 6, and when the set time has elapsed, the reflux valve 54 is automatically closed. After that, the concentration of 02 in the buffer tank 33 is 2.5.
%, the modified air supply switch 49a is turned on, the three-way solenoid valve 13 is switched, the modified air in the buffer tank 33 is supplied to the shiitake mushroom storage 2B, and the C02 concentration is lowered to the lower limit of 9%. Then, when the CO2 concentration reaches the lower limit value, the shiitake mushroom modified air generation switch 49c and the shiitake mushroom air supply switch 49f are turned off.

Furthermore, when the adjustment of the gas concentration in the shiitake storage 2B is completed, if the 02 concentration in the broccoli storage 2c has reached the lower limit of 2% or the CO2 concentration or the upper limit of 596, the operator can Generation switch 49
d. Turn on the broccoli air supply switch 49e. As a result, air is supplied to the storage 2C, and the upper limit of the 02 concentration suitable for broccoli is set to 4%, and the 02 concentration of the modified air is switched from 2.5% for shiitake mushrooms to 4% for broccoli. At that time, the modified air generation unit 3
Shorten the half cycle time from 22 seconds to 4 seconds.

This switches the 02 concentration from 2.5% to 4% in a short time. The operating time of 4 seconds for the half cycle time is set in advance in the controller 6, and the half cycle time is automatically changed from 4 seconds to 14 seconds after a predetermined period of time has elapsed.

Thereafter, when the modified air in the buffer tank 33 reaches 02a degrees or 4%, the modified air supply switch 49a is operated to switch the three-way solenoid valve 13. Therefore, the modified air in the buffer tank 33 is supplied to the storage 2C, and the CO2 inside the storage is
Lower the concentration to the lower limit of 3%. The operator then checks the CO in the warehouse.
When the concentration reaches 2 or 3%, turn off all switches.

Further, if the 02 concentration in another storage reaches the lower limit value or the C02 concentration or the upper limit value, the concentration of that storage area is subsequently adjusted. However, if another storage is within the CA conditions, it will be in a standby state.

In this way, when the modified air generation unit 3 is driven from the standby state, when modified air with different 02 concentrations is continuously generated for different types of fruits and vegetables, and when the 02 concentration is changed to lower the 02 concentration, as described above. Adsorption tank 21 for modified air
．． When changing the direction of increasing the 02 concentration by refluxing the 02 to 22, the desired 02 concentration can be obtained in a shorter time by shortening the half cycle time.

The controller 6 automatically determines whether to perform the reflux operation or shorten the half cycle time based on the settings of the 02 concentration setting switch 48b and the CO2 concentration setting switch 48c of the switch box 48.

Effects of the Invention As described above, the storage device according to the present invention can switch the oxygen concentration to a desired concentration in a short time, and therefore has the following advantages:
The modified air generation unit of the stand can supply gas at a concentration suitable for each type of fruit or vegetable to a plurality of storages storing different types of fruits and vegetables.

Therefore, it is possible to shorten the time from when the modified air generation unit is activated to when the modified air of 02 concentration that can be actually supplied into the storage is obtained, and as a result, the entire operating time of the storage device can be shortened. It has features such as being able to lower running costs.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the storage device according to the present invention, Fig. 2 is a diagram showing changes in oxygen concentration due to reflux operation, and Fig. 3 is a diagram showing changes in oxygen concentration due to reflux operation.
The figure is a diagram showing changes in oxygen concentration due to shortening of half cycle time, and FIG. 4 is a flowchart for explaining the process executed by the programmable controller. ■... Storage device, 2A-2C... Storage, 3. Modified air generation unit, 4... Air supply unit, 5...
Gas concentration detection unit, 6...Programmable controller, 7A-7C...02 sensor, 8A-8C...
・Co2 sensor, 13... Three-way solenoid valve, 17... Compressor, 18... Dryer, 20A to 20C...
・Opening/closing valve, 21.22...Adsorption tank, 21A, 22A・
...Adsorbent, 30...Takeout piping, 31.32...Pressure equalization valve, 33...Buffer tank, 37a, 37b.
...Check valve, 38...Reducing valve, 43.44...Takeout valve, 45a...02 sensor, 45..., 46A~4
6C...02 concentration meter, 47A-47C...C○2 concentration meter, 48...switch box, 48a...start switch, 48b...02 concentration setting switch, 4
8c...C02 concentration setting switch, 49a...Modified air supply switch, 49b...Modified air generation switch for apples, 49c...Modified air generation switch for shiitake mushrooms, 49d...Modified air generation switch for broccoli, 4
9e...Air supply switch for apples, 49f...Air supply switch for shiitake mushrooms, 49g...Air supply switch for broccoli. Patent applicant Director, Ministry of Agriculture, Forestry and Fisheries Vegetable and Tea Industry Experiment Station
Tokiko Co., Ltd., Do-＼

Claims (1)

[Scope of Claims] The invention includes a storage where stored materials are stored, an adsorption tank filled with an adsorbent, and a tank in which nitrogen gas separated and produced by the adsorbent in the adsorption tank is stored. In a storage device that supplies gas from the tank to the storage so that the gas concentration ratio in the storage becomes a preset concentration, when the gas concentration in the storage is set to a low oxygen concentration, the tank The nitrogen gas in the tank is refluxed into the adsorption tank, and when the gas concentration in the storage is set to a high oxygen concentration, the raw material gas is supplied to the adsorption tank, and then the nitrogen gas separated and produced by the adsorbent is A storage device characterized by comprising a concentration control means for shortening the time until taking out.