JP2838775B2 - Freshness keeping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to vegetables, fruits, flowers, etc.
Vegetable products that need to be kept as fresh as possible until sold or processed (hereinafter referred to as fresh vegetables)
The present invention relates to a device for maintaining freshness of fresh vegetables and the like, which is used in a facility that stores a large amount of vegetables.

[0002]

2. Description of the Related Art In facilities such as warehouses and storages that store large quantities of fresh vegetables, leaving ethylene released from fresh vegetables during storage accelerates the maturation, aging, flowering, etc. of fresh vegetables. It may accelerate changes that lead to loss of commercial value, such as overmaturation, decay, and flowering. For this reason,
Ethylene generated in closed storage facilities must be removed in some way to prevent the increase in ethylene concentration in the air, and several measures have been proposed.

One of them is disclosed in Japanese Patent Application Laid-Open No. Hei 2-131535, in which a passage for taking in and circulating air in a facility is provided with two ultraviolet irradiation sections for irradiating ultraviolet rays having different wavelengths and an ethylene oxide removing section. Have been proposed. This device is installed in a storage facility,
By generating ozone from oxygen in the air in the first ultraviolet irradiation unit, oxidizing ethylene with the generated ozone to convert it to ethylene oxide, and adsorbing the generated ethylene oxide to the ethylene oxide removing unit,
This is to prevent an increase in ethylene concentration. Excess ozone that has not been involved in the oxidation of ethylene is emitted to the second ultraviolet irradiation section by irradiation with ultraviolet light having a wavelength of 253.7 nm to be decomposed into oxygen, and then released outside the apparatus.

[0004] This ethylene removal system has a problem that excess ozone is released together with the treated air without being completely decomposed in the second ultraviolet irradiation section, thereby deteriorating the working environment of the storage facility. 0.1 to 5.0 ppm in air
The reaction efficiency is poor because ethylene containing only a small amount is reacted with dilute ozone, so it is not possible to expect much in the ethylene removal effect, and a large reaction space is required to increase the reaction rate. Inevitably, the size of the apparatus is inevitably increased (the ozone concentration can be increased by making the ultraviolet irradiation apparatus more powerful, but in such a case, excess ozone that cannot be decomposed further increases).

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to efficiently remove ethylene, which is an obstacle to maintaining freshness in a storage facility for fresh vegetables and the like, as described above, and is small in size and consumes little energy. It is an object of the present invention to provide an improved ozone oxidation type freshness maintaining device.

It is another object of the present invention to reduce the emission of harmful ozone in an ozone oxidation type freshness maintaining device, and to ensure a good working environment.

[0007]

SUMMARY OF THE INVENTION A freshness maintaining device which has been successfully provided by the present invention is an air processing chamber formed in a duct shape, a forced ventilation means for flowing ambient air through the air processing chamber, and a particle size. Is 0.3 to 50 μm and the specific surface area is 100 m ² / g
An air filter mounted on the air outlet of the air treatment chamber carrying the ozone decomposition catalyst composed of the above fine powdered active manganese dioxide , and the concentration of ozone in the air flowing into the air treatment chamber is adjusted to 0.05 to 1 ppm. It is a means for mixing as much as possible.

Preferred specific examples of the ozone decomposing catalyst used in the freshness maintaining device and an air filter (hereinafter referred to as an ozone filter) carrying the catalyst are disclosed in JP-A-5-23.
No. 591. That is, a method in which an oxidizing agent such as hypochlorite or permanganate is allowed to act on a suspension of manganese carbonate in water, the resulting manganese dioxide precipitate is treated with an acid, and further neutralized with an alkali (Japanese Patent Publication No. 55-55). −54
No. 56) . This catalyst is later
Especially the ability to remove ethylene at room temperature by the mechanism described
Are better.

Further, a preferred ozone filter comprises a carrier having a honeycomb structure made of inorganic fiber paper having a porosity of about 70% or more, and the above-mentioned ozone decomposition catalyst supported thereon. Particularly preferably, a residual porosity of 50 to 85% is obtained. Have

As a means for mixing ozone into the air flowing into the air treatment chamber, an ultraviolet lamp that generates ultraviolet light having a wavelength of 184.9 nm capable of converting oxygen to ozone is used.
The easiest way is to install the ultraviolet rays on the air in the air processing chamber so as to be able to irradiate the ultraviolet rays, and to convert a part of the oxygen in the inflowing air into ozone. However, any ozone generator (for example, a surface discharge ozonizer Etc.) outside the air treatment chamber,
The ozone generated therefrom may be introduced into the air treatment chamber.

In any case, a large ozone generating capacity is not required, and 0.05 to 1 p
It is sufficient that ozone of about pm can be mixed.

[0012]

The freshness preserving device of the present invention is installed and used at an arbitrary place such as a floor, a wall, a ceiling, etc. of a storage facility for fresh vegetables. It is also possible to install the device outside the storage facility, but in that case, the device is communicated with the space in the storage facility by a duct or the like. When installed in an air treatment room, if necessary, connect a duct, air hose, etc. to the air inlet side opening and air outlet of the device, and inhale air from any location in the storage facility such as fresh vegetables, after processing. Air to any location in the same facility.

When the forced ventilation means is operated when ethylene is generated in the facility where the apparatus is installed, the air in the facility flows into the air treatment chamber, passes through the ozone filter, and is discharged outside the apparatus. . The ozone mixing means is also activated to make the inflow air have a concentration of about 0.05 to 1 ppm, preferably 0.05.
When about 0.3 ppm of ozone is mixed, a part of ethylene in the air is oxidized by ozone and changed to ethylene oxide. However, since both ethylene and ozone are lean, the probability of causing a reaction in the gas phase is low, and the oxidation reaction occurs only for a small portion of ethylene, and air containing most of ethylene and ozone reaches the ozone filter. The ozone decomposition catalyst of the ozone filter adsorbs ozone in the air and decomposes it into oxygen.

[0014] catalyst manganese dioxide medium described above, since ethylene with ozone adsorption, in which case, the catalyst surface is ready for oxygen and ethylene strong nascent oxidizing power is concentrated, ethylene is oxidized rapidly ing to ethylene oxide.

Thus, the oxidation reaction of ethylene proceeds at a high rate, and at the same time, the decomposition of ozone is also performed. Therefore, the air discharged through the ozone filter to the outside of the apparatus contains little ethylene and also contains excess ozone. Will not be.
The diluted ethylene oxide quickly becomes a harmless substance, for example, reacting with moisture in the environment to become ethylene glycol. Therefore, there is no problem if the diluted ethylene oxide is discharged out of the apparatus as it is.

[0016]

EXAMPLE The effect of the present invention was confirmed by an experiment using the apparatus schematically shown in FIG. In this experimental device, an ozone filter 2 is mounted on the inside of the right end of a duct-shaped casing 1 having a cross section of 25 × 5 cm, a pre-filter 3 for dust removal is mounted on the left end, and a space sandwiched between both filters is an air treatment chamber 4. and then, up the UV lamp 5 which generates ultraviolet rays having a wavelength of 184.9nm in air treatment chamber 4, the right end of the casing 1 is connected to the cross flow fan 6 at the inlet flange, the entire volume of 1 m ³ It is housed in a closed box 7. The ozone filter 2 is composed of an activated manganese dioxide-based ozone decomposition catalyst (specific surface area: 220 m ² / g, average particle size: 5 μm) on a ceramic fiber paper honeycomb structure carrier.
/ m ² .

Before the start of the experiment, ethylene is introduced into the box 7 so that the concentration thereof becomes 2 ppm, and thereafter, the fan 6 is operated to suck the ethylene-containing air in the box 7 from the pre-filter 3 side to thereby remove the ozone filter. Air flow 1m ³ / m on two sides
in, the air that has passed through the ozone filter 2
Was discharged into Box 7. Further, the ultraviolet lamp 5 was turned on to generate ozone from oxygen in the air in the air processing chamber 4 (the average ozone concentration of the air immediately before passing through the ozone filter 2 was 0.06 ppm). .

For comparison, a similar experiment was carried out using an apparatus in which only the carrier not carrying the active manganese dioxide catalyst was attached to the position where the ozone filter 2 was installed in FIG. 1 (Comparative Example 1). The same experiment was performed in a state where the ozone filter 2 of FIG. 1 was removed and the ultraviolet lamp 5 was turned off (Comparative Example 2).

The time-dependent changes in the ethylene concentration of the air in the box 7 in the above three examples are as shown in FIG. 2, and it was confirmed that the efficiency of the ethylene oxidation reaction was significantly improved by using an ozone filter. Further, when the ozone concentration of the air immediately after passing through the ozone filter was measured, in the example, the ozone concentration was lower than the detection limit (0.01 ppm), and in the comparative example 1, it was 0.0.
It was 5 ppm.

[0020]

As described above, according to the present invention, an ozone filter is installed in a freshness preserving apparatus of the type in which ethylene is oxidized and decomposed by ozone, and an ethylene oxidation reaction is caused mainly on an ozone decomposition catalyst. Oxidation of ethylene can be caused to occur much more efficiently than expected for the reaction between the dilute ethylene and ozone in the inside, so that it is possible to completely remove ethylene with a small apparatus. In addition, there is no possibility that excessive ozone is released to deteriorate the working environment of the storage facility for fresh vegetables and the like.

Therefore, by using the apparatus of the present invention, it is possible to more easily and more reliably remove ethylene generated in the storage facility and maintain freshness of fresh vegetables and the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus used in an experiment of an example.

FIG. 2 is a graph showing a result of an experiment of an example.

[Explanation of symbols]

 2: Ozone filter 4: Air treatment room 5: UV lamp 6: Fan

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-284905 (JP, A) JP-A 5-21684 (JP, U) JP-A 64-56684 (JP, U) JP-A 2-56684 137839 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) A23B 7/152 A01F 25/00 A01G 5/06 A01N 3/02

Claims (3)

(57) [Claims] 1. A air treatment chamber formed in a duct-like, forced ventilation means for circulating the ambient air to the air treatment chamber, the particle
Fine powder with a diameter of 0.3 to 50 μm and a specific surface area of 100 m ² / g or more
An air filter installed on the air outlet of the air treatment chamber carrying an ozone decomposition catalyst consisting of powdered activated manganese dioxide , and the concentration of ozone in the air flowing into the air treatment chamber
Freshness maintaining device comprising means for mixing so as to be 0.05 to 1 ppm . Wherein the air treatment chamber formed in a duct-like, forced ventilation means for circulating the ambient air to the air treatment chamber, the particle
Fine powder with a diameter of 0.3 to 50 μm and a specific surface area of 100 m ² / g or more
An air filter that carries an ozone decomposition catalyst composed of powdered activated manganese dioxide and is attached to the air outlet of the air treatment chamber, and generates ozone from part of the oxygen in the air in the air treatment chamber and flows into the air treatment chamber Ozone in the air
For maintaining the freshness of the mixture at a concentration of 0.05 to 1 ppm . 3. An ozone is generated from a part of oxygen in the air by using an ultraviolet lamp which is installed so as to be capable of irradiating ultraviolet rays to the air in the air processing chamber and generates ultraviolet rays having a wavelength of 184.9 nm.
3. The freshness preserving device according to claim 2, wherein