JPH07114602B2 - Storage device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device, and more particularly to a storage device that fills a storage with a gas for maintaining freshness of the stored product.

2. Description of the Related Art Fresh food products such as vegetables and fruits are generally stored in a storage device to maintain their freshness until shipment.
In addition, for long-term storage of these stored materials, in addition to inactivating the inside of the storage at a temperature low enough not to freeze the storage, the oxygen temperature in the storage is lowered to the necessary minimum, and further carbon dioxide is given to cause respiratory action. It is considered to be the best way to suppress this, and these kinds of studies have been ongoing these days. A storage method utilizing this reduction is called a CA (Atmosphere Controlled or Controlled Atmosphere) storage method.

In the storage device using this means, the inside of the storage is kept at the minimum necessary oxygen (O ₂ ), the maximum required carbon dioxide gas (CO ₂ gas) is put, and the rest is nitrogen gas (N ₂ gas), etc. It is necessary to supplement with inert gas.

In this way, in the storage device, first, N ₂ gas or CO ₂ gas is injected into the storage in order to reduce the O ₂ gas concentration in the storage, but PSA (Pressure Swing Adsorp
It is conceivable to supply N ₂ gas into the refrigerator by using a nitrogen gas generator.

In addition, the optimum O ₂ gas in the storage is
Since the ratios of CO ₂ gas and N ₂ gas are determined respectively, it is necessary to always keep a constant ratio according to each fruit and vegetable. However, since the stored matter breathes as described above, the O ₂ gas is consumed and CO ₂ gas is generated with the passage of time, and the ratio of the gas concentration in the storage changes. Therefore, it is necessary to monitor changes in the gas concentration in the refrigerator during the storage period and make adjustments so that this is always constant.

However, when adjusting the gas concentration ratio in the storage using the above-mentioned PSA type nitrogen gas generator, it is only necessary to supply the N ₂ gas separated and produced in the adsorption tank into the storage. However, when adjusting the concentration ratio suitable for fruits and vegetables stored in the refrigerator, it takes a considerable time to change the operating conditions of the nitrogen gas generator to obtain a gas having a desired oxygen concentration. Therefore, it is not possible to supply a gas having a concentration suitable for each fruit and vegetables to each of the plurality of stores in which different kinds of fruits and vegetables are stored by one nitrogen gas generator, and therefore the gas in the plurality of stores is different. In order to maintain the concentration ratio, a nitrogen gas generator is required for each storage, which not only complicates the configuration but also makes the equipment expensive and requires a wider installation space.

Then, this invention aims at providing the storage device which solved the said subject.

Means for Solving the Problems The present invention has a plurality of storages in which one storage is stored individually among a plurality of storages of different types, and an adsorption tank filled with an adsorbent, A product gas supply unit that supplies a raw material gas to the adsorption tank to generate a product gas to be supplied to the storage, and a gas concentration ratio suitable for the stored material stored in each storage for each of the plurality of storage tanks. Gas concentration establishing means for setting a permissible range, concentration detecting means for detecting gas concentration ratios in each of the plurality of storages, and gas concentration ratios detected by the concentration detecting means are preset by the gas concentration setting means. When a limit value exceeding the specified allowable range is reached, a storage storage designating means for designating the storage storage to which the product gas from the product gas supply unit is to be supplied, and the plurality of storage storages by the storage storage designating means. When one of the storages is designated, the time from the supply of the raw material gas to the adsorption tank until the product gas is taken out so that the gas concentration ratio within the allowable range set by the gas concentration setting means is obtained. It is characterized by comprising a control means for changing.

The working gas concentration setting means can set a gas concentration ratio suitable for the stored items in each of the plurality of storages for each storage, and when supplying the product gas from the tank to each storage, the adsorption tank It is possible to change the time of the gas generation cycle in the above according to the gas concentration ratio preset for each storage, and to generate the gas having a desired concentration ratio suitable for each stored material in a short time.

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. First
FIG. 1 is a configuration diagram of a storage device 1 which is an embodiment of the present invention. The storage device 1 is roughly composed of a storage 2 (2A to 2C), a modified air generation unit (product gas supply unit) 3, an air supply unit 4, a gas concentration detection unit 5, and a programmable controller (hereinafter simply referred to as controller) 6. ing.

Each of the storages 2A to 2C stores therein different kinds of fruits and vegetables and the like, and the storages 2A to 2C are configured to be maintained at a low temperature by which a storage is not frozen by a refrigerating device (not shown).

In this embodiment, "apple" is stored in the first storage 2A, "shiitake" is stored in the second storage 2B, and
It is assumed that "broccoli" is stored in the storage 2C. Further, the storages 2A to 2C are configured to be airtight with the door for taking in and out stored items closed, and further, a fan (not shown) is provided in the storage so that the inside air can be agitated. ing. Inside each of the storages 2A to 2C, O ₂ sensors 7A to 7C and CO ₂ sensors 8A to 8C are provided.

9 is a modified air supply pipe connected to the modified air generating unit 3 (hereinafter referred to as modified air pipe), 10 is an oxygen supply pipe connected to the air supply unit 4 (hereinafter referred to as O ₂ pipe), 11A to 11C Are connected to the storages 2A to 2C by exhaust pipes, and exhaust valves 53A to 53C are arranged in the respective discharge arrangements 11A to 11C. The correction air pipe 9 is provided with a throttle valve 12 and a three-way solenoid valve 13. The modified air from the modified air generating unit 3 is throttled to a predetermined flow rate by the throttle valve 12 and supplied to the humidifier 19 when the three-way solenoid valve 13 is excited. In addition, the humidifier
The modified air from 19 is supplied to each storage 2A to 2C via a pipe 20 and opening / closing valves 20A to 20C. Further, an air supply valve 14 and a throttle valve 15 are arranged in the O ₂ pipe 10, and the air from the air supply unit 4 is opened by opening the air supply valve 14 and the throttle valve 15
Is supplied to the humidifier 51 via. Further, the air from the humidifier 51 passes through the pipe 52 and the opening / closing valves 52A to 52C to store each of the storages 2A.
Supplied to ~ 2C.

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

The air supply unit 4 includes a compressor 17 and a compressor
It consists of a dryer 18 for drying the compressed air from 17.
The dryer 18 is connected to the pipes 16 and 10, and the dryer 1
The air from 8 is supplied to the storages 2A to 2C and the modified air generating unit 3.

Here, the configuration of the modified air generating unit 3 will be described.

In FIG. 1, reference numerals 21 and 22 designate the first and second adsorption tanks, respectively.
Each of them is filled with adsorbents 21A and 22A (shown as satin in the drawing) made of molecular sieving carbon that adsorbs oxygen.

23 and 24 are pipes for discharging the gas from the adsorption tanks 21 and 22 at the time of desorption, and are connected to the common discharge pipe 25, respectively.
Discharges the adsorbed gas (adsorbed oxygen in this embodiment). In the middle of the pipes 23 and 24, gas discharge valves 26 and 27, which are electromagnetic valves for alternately discharging the desorption gas in the adsorption tanks 21 and 22 every half cycle, are provided.

On the other hand, 28 and 29 are pipes that connect the adsorption tanks 21 and 22, and 30 is an extraction pipe that is connected to the pipes 28 and 29. Extraction valves 31 and 32 for extracting the modified air are provided respectively. In addition, the extraction pipe 30 generates modified air (containing low concentration O ₂ gas).
It is connected to a buffer tank 33 that stores N ₂ gas).

Further, a pressure reducing valve 38 is arranged in the pipe 16, and an air supply valve 4 is connected to the pipes 39 and 40 which are in communication with the pipe 16 and connected to the adsorption tanks 21 and 22.
1,42 are provided.

36 is a pressure equalizing pipe that communicates between the pipes 28 and 29, and 37 is a pressure equalizing valve provided in the middle of the pipe 36, which is opened for a predetermined short time at the end of the half cycle to equalize between the adsorption tanks 21 and 22. Use pressure.

In the buffer tank 33, the modified air pipe 9 for supplying the modified air generated by the modified air generation unit 3 to the storages 2A to 2C.
Is connected in the middle of the modified air pipe 9, and in addition to the throttle valve 12 and the three-way solenoid valve 13, an extraction valve 44 composed of a solenoid valve.
And contained in the modified air from the buffer tank 33
An O ₂ sensor 45a that detects the O ₂ concentration is provided. This O
The _second sensor 45a is connected to the O ₂ concentration meter 45, the O ₂ concentration meter 45
Detects the concentration by the detection signal from the O ₂ sensor 45a.

The gas concentration detection unit 5 is an O ₂ concentration meter 46A-46C, CO ₂ concentration meter
With 47A-47C. Each O ₂ concentration meter 46A to 46C, CO ₂ concentration meter 47A
~ 47C is connected to the above O ₂ sensor 7A ~ 7C, CO ₂ sensor 8A ~ 8C, and outputs whether the concentration is within the set range by the detection signal from each sensor 7A ~ 7C, 8A ~ 8C. . The signal output from the gas concentration detection unit 5 is input to the controller 6. The controller 6 activates the modified air generating unit 3 and the air supply unit 4 based on the detection signals from the respective sensors, and also the three-way solenoid valve 13 and the air supply 1
4A and adsorption tanks 21, 22 half cycle time is changed to store 2A
A program is input as concentration control means for controlling the opening and closing of each solenoid valve so that the O ₂ concentration and the CO ₂ concentration within 2C become the set predetermined values.

A switch box 48 is provided with a start switch 48a of the storage device 1, an O ₂ concentration establishing switch 48b for setting the O ₂ concentration and CO ₂ concentration in the storage 2, and a CO ₂ concentration setting switch 48c (gas concentration setting means). And is connected to the controller 6. Further, the switch box 48 includes a modified air supply switch 49a as a storage designating means, a modified air generation switch 49b for apples, a modified air generation switch 49c for shiitake mushrooms,
A modified air generation switch 49d for broccoli, an air supply switch 49e for apples, an air supply switch 49f for shiitake mushrooms, and an air supply switch 49g for broccoli are provided.

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

When the start switch 48a of the switch box 48 is operated, the compressor 17 is started, and the air compressed by the compressor 17 passes through the dryer 18 to be dehumidified and then the pipe 6
Through the pressure reducing valve 38 to a predetermined pressure. And
In the modified air generating unit 3, the following steps 1 to 3 are sequentially performed to generate modified air (N ₂ gas).

“Decompression of the first adsorption tank 21 and increase of pressure of the second adsorption tank 22” That is, the air supply valve 42 and the main body discharge valve 26 are opened, and compressed air is supplied into the adsorption tank 22 and adsorbed. The residual gas in the tank 21 is discharged through the discharge pipe 25. for that reason,
In the adsorption tank 22, compressed air oxygen is adsorbed by the adsorbent 22A to generate high-purity nitrogen gas. Then, the extraction valve 32 is opened, and the modified air separated and generated in the adsorption tank 22 is supplied to the buffer tank 33. During this time, the adsorbent 21
The oxygen adsorbed on A is discharged into the desorbed atmosphere.

"Equalization between the adsorption tanks 21 and 22" The gas supply valve 42, the discharge valve 26, and the extraction valve 32, which have been opened as described above, are closed and the pressure equalization valve 37 is opened. As a result, the pressure-adjusted air in the adsorption tank 22 is supplied to the depressurized adsorption tank 21 through the pressure equalizing valve 37, 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 the pressure equalizing valve 37 opened above is closed, the air supply valve 41 and the gas exhausting 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, adsorption tank
In 21, the oxygen of the compressed air is adsorbed by the adsorbent 21A to generate high-purity nitrogen gas. Then, the extraction valve 31 is opened and the modified air generated in the adsorption tank 21 is stored in the buffer tank 33.
Is supplied to. During this time, the oxygen adsorbed by the adsorbent 22A is desorbed in the adsorption tank 22 and discharged into the atmosphere.

"Equalization between the adsorption tanks 21 and 22" The gas supply valve 41, the discharge valve 27, and the extraction valve 31 which are opened above are closed, and the pressure equalization valve 37 is opened. As a result, the pressure-adjusted air in the adsorption tank 21 is pressurized by the pressure equalizing valve 37.
It is supplied to the inside of the adsorption tank 22 whose pressure has been reduced through, and the yield in the adsorption tank 22 is enhanced.

In the modified air generation unit 3, perform steps 1 to 3 above.
The cycle is repeated to store the modified air in the buffer tank 33. Incidentally, the extraction valve 44 during operation of the modified air generating unit 3 is always open.

FIG. 2 is an experimental result showing a change in oxygen concentration when the time of the half cycle (step or) of the modified air generating unit 3 is changed. It can be seen from FIG. 2 that modified air having a high oxygen concentration can be obtained as the half cycle time is shortened. Therefore, the modified air having a desired concentration can be generated by changing the half cycle time.

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

In this embodiment, the temperature is lowered in each of the storages 2A to 2C, and the gas concentration ratio is set so that the storage condition (allowable range of gas concentration ratio) suitable for the storage of each fruit and vegetables is maintained by the CA storage method. It is designed to be controlled. That is, the storage conditions for apples are 3 ≤ O ₂ ≤ 5%, 4 ≤ CO ₂ ≤ 6%, the storage conditions for shiitake mushrooms are 1.5 ≤ O ₂ ≤ 2.5%, 9 ≤ CO ₂ ≤ 11%, and the broccoli storage conditions are The O ₂ concentration setting switch 48b and the CO ₂ concentration setting switch 48 are set so that 2 ≦ O ₂ ≦ 4% and 3 ≦ CO ₂ ≦ 5%, respectively.
It is set by the operation of c.

The 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
Supply to. Also, modified air generation switch 49b for apples
Sets the half cycle time of the modified air generating unit 3 to a time at which the upper limit value O ₂ 5% of oxygen concentration necessary for apple storage is obtained, and operates the modified air generating unit 3. Also, storage
Open / close valve 20A and exhaust valve 53A to supply modified air to 2A
Open the valve.

Further, in this embodiment, in order to obtain the modified air having the preset oxygen concentration in a short time, the half cycle time and the shortening operation are performed for the predetermined time.

Because fruits and vegetables are breathing, they consume O ₂ and CO ₂
To release. As a result, the atmosphere inside the chamber is reduced in O ₂ and CO
₂ increases. Therefore, since the O ₂ concentration in the refrigerator, CO ₂ concentration is to fall within a range suitable for each fruit or vegetable, raised to the upper limit value of the O ₂ concentration is supplied into the air compartment, O ₂ further upper limit reducing the CO ₂ concentration to remove CO ₂ is supplied gets air controlled to a concentration in the refrigerator without changing the O ₂ concentration. By performing such a concentration control operation, the controller 6 controls the O ₂ concentration in the refrigerator to the upper limit value and the CO ₂ concentration to the lower limit value.

Further specifically, the controller 6 executes the processing shown in FIG.

When the gas concentration ratio of the apple storage 2A reaches the lower limit value of 3% for O ₂ or the upper limit value of CO ₂ for CO ₂ of 6% due to the breathing action of the apple, the worker turns on the apple air supply switch 49e. . This allows air supply valve 14, on-off valve 20A, exhaust valve 5
3A opens and compressed air from compressor 17 is stored in storage 2A
Is supplied to. Therefore, when the O ₂ concentration in the chamber rises and reaches the upper limit of 5%, the switch 49e is turned off.

Next, when the modified air generation switch 49b for apples is turned on in step S1 (the following steps will be omitted), the controller 6 activates the compressor 17 and the dryer 18. In S2, the preset O ₂ concentration of 5% Half cycle time is set to 11 seconds to generate modified air.

Then, in the next S3, the operations of steps 1 to 5 are repeated with a cycle time of 11 seconds until the modified air of O ₂ 5% is obtained.

When the O ₂ concentration value of the O ₂ concentration meter 45 reaches 5% in S3,
When the modified air supply switch 49e is turned on (S4), the three-way solenoid valve 13 is switched, and the modified air in the buffer tank 33 is supplied to the storage 2A (S5). The modified air continues to be supplied until the CO ₂ concentration in the storage 2A reaches the lower limit of 4% (S6), and the modified air supply switch 49a and the modified air generation switch 49b for apple are turned off when the CO ₂ concentration in the storage reaches the lower limit of 4%. When it is operated to, the compressor 17, the dryer 18, and the modified air generating unit 3 are stopped (S7), and the process returns to S1.

Also, in the other storages 2B and 2C, the O ₂ concentration is below the lower limit or CO ₂
When the concentration reaches the upper limit, the above apple storage 2A
In the same manner as above, the air is supplied to the inside of the storage, and further, the modified air generating unit 3 is operated to supply the modified air of a predetermined concentration to the storages 2B and 2C.

For example, the gas concentration in the apple storage 2A is O ₂ = 5%, CO ₂
If the O ₂ concentration of the shiitake mushroom storage 2B reaches the lower limit of 1.5% or the CO ₂ concentration reaches the upper limit of 11% when adjusted to 4%, the operator operates the Shiitake mushroom air supply switch 49f. As a result, air is supplied to the storage 2B to set the upper limit of the O ₂ concentration in the storage to 2.5%.

Next, when the Shiitake modified air generation switch 49c is turned on, the process proceeds from S1 to S8, and half cycle time is set to 22 seconds to generate modified air having an O ₂ concentration of 2.5% (S9).
Therefore, the modified air generation unit 3 has an O ₂ concentration of 5% for apples that had been generated up to that, and an O ₂ concentration of 2.5 for shiitake mushrooms.
Change the concentration to% modified air.

After that, when the O ₂ concentration in the buffer tank 33 reaches 2.5% (S
10) Turn on the modified air supply switch 49a (S11) and switch the three-way solenoid valve 13 (S12) to supply the modified air in the buffer tank 33 to the storage room 2B for shiitake mushrooms to lower the CO ₂ concentration to the lower limit value of 9%. . Then, in S13, the CO ₂ concentration is the lower limit value 9
%, The shiitake reconditioning air generation switch 49c and the shiitake air supply switch 49f are turned off (S1
4) Return to S1.

Furthermore, when the gas concentration adjustment in the storage 2B for shiitake is completed, the O ₂ concentration in the storage 2C for broccoli has a lower limit of 2
% Or CO ₂ concentration reaches the upper limit of 5%, the operator turns on the broccoli air supply switch 49e.
As a result, air is supplied to the storage 2C, and the upper limit of the O ₂ concentration suitable for broccoli is set to 4%.

Next, when the modified air generation switch 49d for broccoli is turned on, the process proceeds from S8 to S15, and half cycle time is once set to 4 seconds to generate modified air having an O ₂ concentration of 4% (S16).

This causes the O ₂ concentration to switch from 2.5% to 4% in a short time. The operation time of the half cycle time of 4 seconds is set in the controller 6 in advance, and when a predetermined time elapses (S1
7), the half cycle time is changed from 4 seconds to 14 seconds (S1
8).

After that, the O ₂ concentration of the modified air in the buffer tank 33 is 4%.
When it becomes (S19), the modified air supply switch 49a is operated to switch the three-way solenoid valve 13 (S20). As a result, the modified air in the buffer tank 33 is supplied to the storage 2C and stored in the storage 2C.
Lower the CO ₂ concentration to the lower limit of 3%. Then, in S21, CO ₂ in the storage
When all the switches are turned off when the concentration reaches 3% (S22), the process returns to S1 again.

If the O ₂ concentration of another storage reaches the lower limit or the CO ₂ concentration reaches the upper limit, the concentration of that storage is continuously adjusted. However, when the other storage is within the CA condition, S1, S8, and S15 are repeated and the standby state is set.

In this way, when the modified air generating unit is driven from the standby state and when modified air with different O ₂ concentration is continuously generated for different kinds of fruits and vegetables, the half cycle time is preset for each storage 2A to 2C. The desired O ₂ concentration can be obtained in a shorter time by changing the time according to the concentration and operating the operation.

In the above embodiment, apples, shiitake mushrooms, broccoli and other fruits and vegetables are stored in each of the storages 2A to 2C, but the present invention is not limited to this, and it is of course possible to store fruits and vegetables of other species. Is. In that case, the O ₂ temperature and the CO ₂ concentration suitable for the fruits and vegetables may be established in advance.

As described above, in the storage device according to the present invention, when the gas accumulated in the tank is supplied to each storage, the gas generation cycle time in the adsorption tank is preset for each storage by the gas concentration setting means. It is possible to generate a desired concentration ratio gas suitable for each stored material in a short time by changing the concentration ratio. Therefore, it is possible to supply a gas having a concentration suitable for each of the fruits and vegetables in a plurality of storages for storing different types of fruits and vegetables by providing only one modified air unit. Further, since it is not necessary to provide a modified air unit for each storage, not only the equipment cost is low, but also the configuration can be simplified and the installation space is small. Moreover, since the desired gas concentration can be obtained simply by changing the cycle time of the adsorption tank, the gas concentration can be changed relatively easily.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a storage device according to the present invention, FIG. 2 is a diagram showing a change in oxygen concentration due to a change in half cycle time, and FIG. 3 describes a process executed by a programmable controller. It is a flowchart for. 1 ... Storage device, 2A to 2C ... Storage device, 3 ... Modified air generation unit, 4 ... Air supply unit, 5 ... Gas concentration detection unit, 6 ... Programmable controller, 7A
~ 7C …… O ₂ sensor, 8A ～ 8C …… CO ₂ sensor, 13 …… three-way solenoid valve, 17 …… compressor, 18 …… dryer, 20A ～ 2
0C ... open / close valve, 21,22 ... adsorption tank, 21A, 22A ... adsorbent,
30 …… take-out pipe, 31,32 …… take-out valve, 33 …… buffer tank, 37 …… equalizing valve, 38 …… pressure reducing valve, 44 …… take-out valve, 45a …… O ₂ sensor, 45… , 46A-46C ... O ₂ densitometer, 47
A to 47C …… CO ₂ concentration meter, 48 …… Switch box, 48a…
… Start switch, 48b …… O ₂ concentration setting switch, 48c
…… CO ₂ concentration setting switch, 49a …… Modified air supply switch, 49b …… Apple modified air generation switch, 49c …… Shiitake modified air generation switch, 49d …… Broccoli modified air generation switch, 49e …… Apple Air supply switch for 49f …… Shiitake air supply switch, 49g …… Broccoli air supply switch.

Front page continued (72) Inventor Yoshio Senoo 1-3-6 Fujimi, Kawasaki-ku, Kanagawa Prefecture Tokiko Co., Ltd. (72) Masaki Kawai 1-3-6 Fujimi, Kawasaki-ku, Kanagawa Prefecture Tokiko Stock In-house (56) References JP 62-236412 (JP, A) JP 62-134028 (JP, A) Actual development Sho 50-107660 (JP, U)

Claims (1)

[Claims] 1. A plurality of storages in which one storage is stored individually among a plurality of storages of different types, and an adsorption tank filled with an adsorbent, and a raw material gas is contained in the adsorption tank. And a product gas supply unit that generates a product gas to be supplied to the storage, and a gas concentration that sets a permissible range of a gas concentration ratio suitable for the stored product stored in each storage for each of the plurality of storages. Setting means, concentration detecting means for detecting respective gas concentration ratios in the plurality of storages, and a limit at which the gas concentration ratio detected by the concentration detecting means exceeds an allowable range preset by the gas concentration setting means. When the value is reached, a storage designating means for designating the storage to be supplied with the product gas from the product gas supply unit, and one storage of the plurality of storages is designated by the storage designating means. Control means for changing the time from supplying the raw material gas to the adsorption tank until taking out the product gas so that the gas concentration ratio within the allowable range set by the gas concentration setting means is obtained. And a storage device.